BUG: Grouped-by column loses name when empty list of aggregations is specified
- [ ] closes #32580
- [ ] 0 tests added / 0 passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`


Hello @echozzy629! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:

* In the file [`pandas/core/base.py`](https://github.com/pandas-dev/pandas/blob/4b7f225558c95ad474535760bc0645eaa58de03e/pandas/core/base.py):

> [Line 441:17](https://github.com/pandas-dev/pandas/blob/4b7f225558c95ad474535760bc0645eaa58de03e/pandas/core/base.py#L441): [E265](https://duckduckgo.com/?q=pep8%20E265) block comment should start with '# '
> [Line 442:89](https://github.com/pandas-dev/pandas/blob/4b7f225558c95ad474535760bc0645eaa58de03e/pandas/core/base.py#L442): [E501](https://duckduckgo.com/?q=pep8%20E501) line too long (106 > 88 characters)
> [Line 443:17](https://github.com/pandas-dev/pandas/blob/4b7f225558c95ad474535760bc0645eaa58de03e/pandas/core/base.py#L443): [E265](https://duckduckgo.com/?q=pep8%20E265) block comment should start with '# '
> [Line 443:89](https://github.com/pandas-dev/pandas/blob/4b7f225558c95ad474535760bc0645eaa58de03e/pandas/core/base.py#L443): [E501](https://duckduckgo.com/?q=pep8%20E501) line too long (137 > 88 characters)
> [Line 444:17](https://github.com/pandas-dev/pandas/blob/4b7f225558c95ad474535760bc0645eaa58de03e/pandas/core/base.py#L444): [E265](https://duckduckgo.com/?q=pep8%20E265) block comment should start with '# '
> [Line 445:28](https://github.com/pandas-dev/pandas/blob/4b7f225558c95ad474535760bc0645eaa58de03e/pandas/core/base.py#L445): [E225](https://duckduckgo.com/?q=pep8%20E225) missing whitespace around operator
> [Line 447:34](https://github.com/pandas-dev/pandas/blob/4b7f225558c95ad474535760bc0645eaa58de03e/pandas/core/base.py#L447): [E225](https://duckduckgo.com/?q=pep8%20E225) missing whitespace around operator
> [Line 448:32](https://github.com/pandas-dev/pandas/blob/4b7f225558c95ad474535760bc0645eaa58de03e/pandas/core/base.py#L448): [E225](https://duckduckgo.com/?q=pep8%20E225) missing whitespace around operator
> [Line 450:32](https://github.com/pandas-dev/pandas/blob/4b7f225558c95ad474535760bc0645eaa58de03e/pandas/core/base.py#L450): [E225](https://duckduckgo.com/?q=pep8%20E225) missing whitespace around operator
> [Line 451:89](https://github.com/pandas-dev/pandas/blob/4b7f225558c95ad474535760bc0645eaa58de03e/pandas/core/base.py#L451): [E501](https://duckduckgo.com/?q=pep8%20E501) line too long (95 > 88 characters)



##### Comment last updated at 2020-04-13 16:55:13 UTC needs a test for the resolved issue @echozzy629 closing as stale. ping if you want to continue.