Backport PR #25329 on branch 0.24.x (REGR: fix TimedeltaIndex sum and datetime subtraction with NaT (#25282, #25317))
Backport PR #25329: REGR: fix TimedeltaIndex sum and datetime subtraction with NaT (#25282, #25317)
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25385?src=pr&el=h1) Report
> Merging [#25385](https://codecov.io/gh/pandas-dev/pandas/pull/25385?src=pr&el=desc) into [0.24.x](https://codecov.io/gh/pandas-dev/pandas/commit/48e9955298c58f15b56daca05a3bc9f6177c6024?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `87.5%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25385/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25385?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           0.24.x   #25385      +/-   ##
==========================================
+ Coverage   92.39%   92.39%   +<.01%     
==========================================
  Files         166      166              
  Lines       52412    52417       +5     
==========================================
+ Hits        48428    48433       +5     
  Misses       3984     3984
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.82% <87.5%> (-0.01%)` | :arrow_down: |
| #single | `42.88% <37.5%> (-0.01%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25385?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/indexes/base.py](https://codecov.io/gh/pandas-dev/pandas/pull/25385/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9iYXNlLnB5) | `96.55% <100%> (ø)` | :arrow_up: |
| [pandas/core/arrays/datetimes.py](https://codecov.io/gh/pandas-dev/pandas/pull/25385/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL2RhdGV0aW1lcy5weQ==) | `97.79% <100%> (ø)` | :arrow_up: |
| [pandas/core/arrays/timedeltas.py](https://codecov.io/gh/pandas-dev/pandas/pull/25385/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL3RpbWVkZWx0YXMucHk=) | `88.2% <75%> (-0.11%)` | :arrow_down: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/25385/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `88.13% <0%> (+0.09%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25385?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/25385?src=pr&el=footer). Last update [48e9955...79d7dde](https://codecov.io/gh/pandas-dev/pandas/pull/25385?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/25385?src=pr&el=h1) Report
> Merging [#25385](https://codecov.io/gh/pandas-dev/pandas/pull/25385?src=pr&el=desc) into [0.24.x](https://codecov.io/gh/pandas-dev/pandas/commit/48e9955298c58f15b56daca05a3bc9f6177c6024?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `87.5%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25385/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25385?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           0.24.x   #25385      +/-   ##
==========================================
+ Coverage   92.39%   92.39%   +<.01%     
==========================================
  Files         166      166              
  Lines       52412    52417       +5     
==========================================
+ Hits        48428    48433       +5     
  Misses       3984     3984
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.82% <87.5%> (-0.01%)` | :arrow_down: |
| #single | `42.88% <37.5%> (-0.01%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25385?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/indexes/base.py](https://codecov.io/gh/pandas-dev/pandas/pull/25385/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9iYXNlLnB5) | `96.55% <100%> (ø)` | :arrow_up: |
| [pandas/core/arrays/datetimes.py](https://codecov.io/gh/pandas-dev/pandas/pull/25385/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL2RhdGV0aW1lcy5weQ==) | `97.79% <100%> (ø)` | :arrow_up: |
| [pandas/core/arrays/timedeltas.py](https://codecov.io/gh/pandas-dev/pandas/pull/25385/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL3RpbWVkZWx0YXMucHk=) | `88.2% <75%> (-0.11%)` | :arrow_down: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/25385/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `88.13% <0%> (+0.09%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25385?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/25385?src=pr&el=footer). Last update [48e9955...79d7dde](https://codecov.io/gh/pandas-dev/pandas/pull/25385?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
