 BLD: updated conda recipe to be conda-bld 3plus compliant
- [x] closes #18002
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

I did local testing of the build.  Assuming the CI will catch any errors?
@jreback Sounds like a plan.  I'll check out BUILD_TEST.   Separate PR? @bobhaffner ~separate PR is fine.~

actually, can you add to this PR? @jreback No problem.  I'll check it out later today # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18592?src=pr&el=h1) Report
> Merging [#18592](https://codecov.io/gh/pandas-dev/pandas/pull/18592?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/d74ac70ffd44e9d00e6ffa8ecf7a1a88312e8065?src=pr&el=desc) will **decrease** coverage by `0.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/18592/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/18592?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #18592      +/-   ##
==========================================
- Coverage   91.44%   91.43%   -0.02%     
==========================================
  Files         157      157              
  Lines       51379    51379              
==========================================
- Hits        46985    46978       -7     
- Misses       4394     4401       +7
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.3% <ø> (ø)` | :arrow_up: |
| #single | `40.57% <ø> (-0.11%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18592?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/18592/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/18592/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.81% <0%> (-0.1%)` | :arrow_down: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/18592/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `81.8% <0%> (+0.19%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18592?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18592?src=pr&el=footer). Last update [d74ac70...dcdf988](https://codecov.io/gh/pandas-dev/pandas/pull/18592?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18592?src=pr&el=h1) Report
> Merging [#18592](https://codecov.io/gh/pandas-dev/pandas/pull/18592?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/99d384d4f7ef6e2b6cb5a4eebea127e8bddf521b?src=pr&el=desc) will **decrease** coverage by `0.16%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/18592/graphs/tree.svg?token=eZ4WkYLtcO&width=650&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/18592?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #18592      +/-   ##
==========================================
- Coverage   91.59%   91.43%   -0.17%     
==========================================
  Files         153      157       +4     
  Lines       51361    51379      +18     
==========================================
- Hits        47046    46978      -68     
- Misses       4315     4401      +86
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.3% <ø> (-0.16%)` | :arrow_down: |
| #single | `40.57% <ø> (-0.17%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18592?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/tseries/converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/18592/diff?src=pr&el=tree#diff-cGFuZGFzL3RzZXJpZXMvY29udmVydGVyLnB5) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/io/excel.py](https://codecov.io/gh/pandas-dev/pandas/pull/18592/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2V4Y2VsLnB5) | `80.39% <0%> (-9.74%)` | :arrow_down: |
| [pandas/io/json/table\_schema.py](https://codecov.io/gh/pandas-dev/pandas/pull/18592/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2pzb24vdGFibGVfc2NoZW1hLnB5) | `95.83% <0%> (-1.39%)` | :arrow_down: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/18592/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `65.25% <0%> (-1.27%)` | :arrow_down: |
| [pandas/core/reshape/melt.py](https://codecov.io/gh/pandas-dev/pandas/pull/18592/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcmVzaGFwZS9tZWx0LnB5) | `96.22% <0%> (-1.03%)` | :arrow_down: |
| [pandas/core/indexes/interval.py](https://codecov.io/gh/pandas-dev/pandas/pull/18592/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9pbnRlcnZhbC5weQ==) | `93.05% <0%> (-0.75%)` | :arrow_down: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/18592/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `81.8% <0%> (-0.74%)` | :arrow_down: |
| [pandas/compat/\_\_init\_\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/18592/diff?src=pr&el=tree#diff-cGFuZGFzL2NvbXBhdC9fX2luaXRfXy5weQ==) | `58.18% <0%> (-0.59%)` | :arrow_down: |
| [pandas/io/json/json.py](https://codecov.io/gh/pandas-dev/pandas/pull/18592/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2pzb24vanNvbi5weQ==) | `91.75% <0%> (-0.34%)` | :arrow_down: |
| [pandas/core/indexes/category.py](https://codecov.io/gh/pandas-dev/pandas/pull/18592/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9jYXRlZ29yeS5weQ==) | `97.2% <0%> (-0.31%)` | :arrow_down: |
| ... and [38 more](https://codecov.io/gh/pandas-dev/pandas/pull/18592/diff?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18592?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18592?src=pr&el=footer). Last update [99d384d...d0c77a6](https://codecov.io/gh/pandas-dev/pandas/pull/18592?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 I'm having a little trouble figuring out how to tackle this BUILD_TEST.  

I'm thinking about adding a piece at [line 170](https://github.com/pandas-dev/pandas/blob/bdbd6549f74174cd05edcab20c713c332ab548cb/ci/install_travis.sh#L170)  of install_travis.sh to remove the pip build after it's complete and then proceed with the conda recipe build.  Not sure though, my CI experience is limited. Eager to learn it though.  Any advice would be appreciated.     don’t remove the existing code rather we can add this for say CONDA_BUILD_TEST

would repurpose one of the other allowed failure builds just change the name of that build (eg ci/requirements needs changes as well as .travis.yml) Thanks for the reply, @jreback 

So add a CONDA_BUILD_TEST to the `.travis.yml` and create the following?

 requirements-3.6_CONDA_BUILD_TEST.build    
 requirements-3.6_CONDA_BUILD_TEST.pip
 requirements-3.6_CONDA_BUILD_TEST.sh

I intend to leave the .pip and the .build empty and do the `conda build ./conda.recipe/ --numpy 1.11 --python 3.6 -q` in the .sh file.   don’t create new, repurpose the 3.5 build: https://travis-ci.org/pandas-dev/pandas/jobs/310085793 Thanks for the feedback, @jreback  Hi @jreback, should I remove BUILD_TEST(soon to be PIP_BUILD_TEST) from allowed failures as well? leave these as they r for the location of allowed failures 
 Hey @jreback, Its obvious this one is out of my depth so I'm packing it in.  I appreciate the advice and the patience.   Let me know if you want me to re-submit the original PR no prob i will finish this up from here
thanks!

but feel free to work on other issues! Thanks, Jeff.   And I intend to.  Even though I've made just a couple of contributions, I've really enjoyed it and feel like I've learned a lot.   superseded by #18787 