Log Message:
py-ruamel-yaml: updated to 0.15.42

0.15.42:
fix regression showing only on narrow Python 2.7 (py27mu) builds
run pre-commit tox on Python 2.7 wide and narrow, as well as 3.4/3.5/3.6/3.7/pypy

0.15.41:
add detection of C-compile failure, which was removed while no longer dependent \ 
on libyaml, C-extensions compilation still needs a compiler though.

0.15.40:
added links to landing places as suggested in issue 190
fixes issue 201: decoding unicode escaped tags on Python2

0.15.39:
merge P.R.27 improving package startup time (and loading when regexp not \ 
actually used)

0.15.38:
fix for losing precision when roundtripping floats
fix for hardcoded dir separator not working for Windows

0.15.37:
again trying to create installable files for 187

0.15.36:
fix issue 187, incompatibility of C extension with 3.7