API/DEPR: replace "raise_conflict" with "errors" for df.update
- [x] closes #23585 
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

This is split off from #23192, as requested per review (because the PR was getting larger and larger).

Hello @h-vetinari! Thanks for updating the PR.

 - There are no PEP8 issues in the file [`pandas/core/frame.py`](https://github.com/h-vetinari/pandas/blob/067c4f222b511422a6b922770db0a3407e161344/pandas/core/frame.py) !

 - There are no PEP8 issues in the file [`pandas/core/panel.py`](https://github.com/h-vetinari/pandas/blob/067c4f222b511422a6b922770db0a3407e161344/pandas/core/panel.py) !

 - There are no PEP8 issues in the file [`pandas/tests/frame/test_combine_concat.py`](https://github.com/h-vetinari/pandas/blob/067c4f222b511422a6b922770db0a3407e161344/pandas/tests/frame/test_combine_concat.py) !

 - There are no PEP8 issues in the file [`pandas/tests/test_panel.py`](https://github.com/h-vetinari/pandas/blob/067c4f222b511422a6b922770db0a3407e161344/pandas/tests/test_panel.py) !



##### Comment last updated on November 14, 2018 at 20:44 Hours UTC # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23657?src=pr&el=h1) Report
> Merging [#23657](https://codecov.io/gh/pandas-dev/pandas/pull/23657?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/e413c491e090274aad78489cc17a2e29cbd8e269?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/23657/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/23657?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #23657      +/-   ##
==========================================
+ Coverage   92.24%   92.25%   +<.01%     
==========================================
  Files         161      161              
  Lines       51339    51346       +7     
==========================================
+ Hits        47360    47367       +7     
  Misses       3979     3979
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.64% <100%> (ø)` | :arrow_up: |
| #single | `42.34% <63.63%> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/23657?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/23657/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.02% <100%> (ø)` | :arrow_up: |
| [pandas/core/panel.py](https://codecov.io/gh/pandas-dev/pandas/pull/23657/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcGFuZWwucHk=) | `97.92% <100%> (+0.01%)` | :arrow_up: |
| [pandas/core/series.py](https://codecov.io/gh/pandas-dev/pandas/pull/23657/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc2VyaWVzLnB5) | `93.68% <0%> (ø)` | :arrow_up: |

------

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> **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/23657?src=pr&el=footer). Last update [e413c49...5ff6261](https://codecov.io/gh/pandas-dev/pandas/pull/23657?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks