[BLD] [CLN] Close assorted issues - bare exceptions, unused func

[jbrockmendel]

- Removing numpy cimport from cython modules where feasible fixes the npy_deprecated1.7 ... warning. update Nope!

• Catch specific exceptions in a handful of places.
• Removes unused function Unused util #19676
• Implement command-line option to enable cython coverage BLD: Make CLI option to enable coverage #21991

closes #19676
closes #21991

• passes git diff upstream/master -u -- "*.py" | flake8 --diff

[gfyoung]

Part of me wants to make this more modular, but the changes are small enough that this isn't an issue. LGTM!

[jreback]

yeah was going to use this a while back, but didn't need

[jreback]

hmm still quite a few warnings (I am guessing that this AND the other PR will make progress on more of these?)

ideally we could run the --with-cython-coverage on a build at some point. though would have to find a way to display this.

[codecov]

Codecov Report

Merging #22030 into master will increase coverage by 0.02%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master   #22030      +/-   ##
==========================================
+ Coverage   92.02%   92.04%   +0.02%     
==========================================
  Files         170      170              
  Lines       50707    50687      -20     
==========================================
- Hits        46661    46654       -7     
+ Misses       4046     4033      -13

Flag	Coverage Δ
#multiple	90.45% <33.33%> (+0.02%)	⬆️
#single	42.31% <33.33%> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/util/_decorators.py	91.34% <ø> (+9.08%)	⬆️
pandas/io/s3.py	86.36% <0%> (ø)	⬆️
pandas/util/_print_versions.py	15.71% <0%> (ø)	⬆️
pandas/core/tools/timedeltas.py	98.41% <100%> (ø)	⬆️

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[jreback]

lgtm. can you rebase again, just want to see what kinds of warnings on build travis has now (this is the last in the series to remove warnings?)

[jbrockmendel]

Will rebase in a bit, ok. But note that the build-related parts of the PR were reverted they broke on windows.

[jreback]

thank @jbrockmendel

[jreback]

@jbrockmendel build warnings are almost gone now! thanks!