[FIX] Support numpy 1.22

[markotoplak]

• np.frompyfunc does convert outputs to the out type anymore
• Adapt a locking test for changed numpy internals

[markotoplak]

@ales-erjavec, could you please review this?

It seems that np.frompyfunc in numpy 1.22 does not do the conversion to the type of its out= argument anymore. Thus, the modified isnastr will always create an intermediate array. I do not see a clear way to avoid this.

[codecov]

Codecov Report

Merging #5760 (f928f31) into master (300dbba) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #5760   +/-   ##
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  Coverage   86.15%   86.15%           
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  Files         315      315           
  Lines       66186    66195    +9     
=======================================
+ Hits        57023    57031    +8     
- Misses       9163     9164    +1     

[ales-erjavec]

Maybe just add casting="unsafe" to __isnastr call? Optionally even check np.can_cast('bool', out.dtype)

[markotoplak]

@ales-erjavec, thanks, I did not know about that ufunc argument. I changed added casting="unsafe" to all such calls, so this PR is now very simple.