BUG: Cannot use tz-aware origin in to_datetime (#16842)
- [x] closes #16842 
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

Hello @step4me! Thanks for updating the PR.





Cheers ! There are no PEP8 issues in this Pull Request. :beers: 

##### Comment last updated on August 21, 2017 at 01:38 Hours UTC # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17244?src=pr&el=h1) Report
> Merging [#17244](https://codecov.io/gh/pandas-dev/pandas/pull/17244?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/0f25426eac5c0097214df78b45125ac039c85770?src=pr&el=desc) will **decrease** coverage by `0.04%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/17244/graphs/tree.svg?width=650&src=pr&token=eZ4WkYLtcO&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/17244?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #17244      +/-   ##
==========================================
- Coverage   91.03%   90.99%   -0.05%     
==========================================
  Files         162      162              
  Lines       49527    49527              
==========================================
- Hits        45086    45065      -21     
- Misses       4441     4462      +21
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.77% <100%> (-0.03%)` | :arrow_down: |
| #single | `40.26% <0%> (-0.06%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/17244?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/tools/datetimes.py](https://codecov.io/gh/pandas-dev/pandas/pull/17244?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvdG9vbHMvZGF0ZXRpbWVzLnB5) | `67.21% <100%> (+0.36%)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/17244?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/17244?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `63.23% <0%> (-1.82%)` | :arrow_down: |
| [pandas/core/indexes/accessors.py](https://codecov.io/gh/pandas-dev/pandas/pull/17244?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9hY2Nlc3NvcnMucHk=) | `88.76% <0%> (-0.49%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/17244?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.72% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17244?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/17244?src=pr&el=footer). Last update [0f25426...daff5b4](https://codecov.io/gh/pandas-dev/pandas/pull/17244?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/17244?src=pr&el=h1) Report
> Merging [#17244](https://codecov.io/gh/pandas-dev/pandas/pull/17244?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/58d872903449b8a29237288ade6227cdb280fe18?src=pr&el=desc) will **decrease** coverage by `0.01%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/17244/graphs/tree.svg?token=eZ4WkYLtcO&height=150&src=pr&width=650)](https://codecov.io/gh/pandas-dev/pandas/pull/17244?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #17244      +/-   ##
==========================================
- Coverage   91.03%   91.01%   -0.02%     
==========================================
  Files         162      162              
  Lines       49567    49570       +3     
==========================================
- Hits        45123    45117       -6     
- Misses       4444     4453       +9
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.79% <100%> (ø)` | :arrow_up: |
| #single | `40.24% <0%> (-0.07%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/17244?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/tools/datetimes.py](https://codecov.io/gh/pandas-dev/pandas/pull/17244?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvdG9vbHMvZGF0ZXRpbWVzLnB5) | `67.12% <100%> (+0.27%)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/17244?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/17244?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.72% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17244?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/17244?src=pr&el=footer). Last update [58d8729...09d051d](https://codecov.io/gh/pandas-dev/pandas/pull/17244?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 @jreback Thanks jreback, I edited files to reflect your comments. But I don't know why "all ci checks have failed".   @jreback I found ci error message about "from datetime import timezone". ImportError: cannot import name timezone in python 2.7. So, I edited "datetime(....., tzinfo=pytz.utc)" thanks!