solve some syntax warnings

[sroet]

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Some SyntaxWarning: "is" with a literal. Did you mean "=="? surfaced on downstream tests on the devel branch . This solves them

[clonker]

Thanks alot @sroet :) this was bothering me for a while too but I never got around to fix it.

[codecov[bot]]

Codecov Report

Merging #1530 (70bbc9b) into devel (b46e895) will decrease coverage by 0.01%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##            devel    #1530      +/-   ##
==========================================
- Coverage   92.06%   92.04%   -0.02%     
==========================================
  Files         229      229              
  Lines       26833    26833              
==========================================
- Hits        24704    24699       -5     
- Misses       2129     2134       +5     

Impacted Files	Coverage Δ
pyemma/coordinates/data/util/reader_utils.py	87.82% <100.00%> (ø)
...emma/_ext/variational/solvers/tests/test_direct.py	88.88% <0.00%> (-8.89%)	:arrow_down:
pyemma/util/statistics.py	59.00% <0.00%> (-1.00%)	:arrow_down:

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[clonker]

spurious test failure, merging this.