CLN/CI: Catch that stderr-warning!

[h-vetinari]

• closes one of the three problems in BLD/CI: ResourceWarnings are back (sometimes)! #23680
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff

There's an uncaught warning to stderr that bubbles up occasionally without failing the build (as far as I can tell), but it was one of the headfakes on the hunt for the ResourceWarnings in #23680.

There's a long list of failing travis builds in that PR (plus in #22225, #23192, #23582), which also suffer from the warning that this PR fixes, which bubbles up at unpredictable times and looks something like this in the output:

..............................................................x...........................................................s....
........................................Skipping line 3: Expected 3 fields in line 3, saw 4
.......................................s.......................................................................................

[pep8speaks]

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

• There are no PEP8 issues in the file pandas/tests/io/parser/python_parser_only.py !

[jreback]

lgtm. ping on green. thanks for tracking down!

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@e413c49). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master   #23706   +/-   ##
=========================================
  Coverage          ?   92.24%           
=========================================
  Files             ?      161           
  Lines             ?    51339           
  Branches          ?        0           
=========================================
  Hits              ?    47360           
  Misses            ?     3979           
  Partials          ?        0

Flag	Coverage Δ
#multiple	90.64% <ø> (?)
#single	42.34% <ø> (?)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e413c49...b097f83. Read the comment docs.

[codecov]

Codecov Report

Merging #23706 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #23706   +/-   ##
=======================================
  Coverage   92.24%   92.24%           
=======================================
  Files         161      161           
  Lines       51339    51339           
=======================================
  Hits        47360    47360           
  Misses       3979     3979

Flag	Coverage Δ
#multiple	90.64% <ø> (ø)	⬆️
#single	42.34% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/core/series.py	93.68% <0%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e413c49...ac5288c. Read the comment docs.

[jbrockmendel]

I'll take your word for it that this catches that warning; big props for getting rid of that annoying thing.

[h-vetinari]

@gfyoung

@h-vetinari : FYI, instead of pushing commits to trigger entirely new builds, just ping one of us. We can restart individual builds for you.

Could you retrigger that timed-out travis job please? ;-)

[jreback]

thanks