Sharp edge: on windows, running `msl up` will complain about checking if in CYGWIN

[val-ms]

The git util and git command output is an eyesore, and detracts from the experience. Come up with a way to replace this with something more user friendly:

PS C:\Users\jenkinsuser\tmp> msl up
2021-05-28 20:36:05 git.util DEBUG Failed checking if running in CYGWIN due to: FileNotFoundError(2, 'The system cannot find the file specified', None, 2, None)
2021-05-28 20:36:05 git.cmd DEBUG Popen(['git', 'pull'], cwd=C:\Users\jenkinsuser\.mussels\cookbooks\scrapbook, universal_newlines=False, shell=None, istream=None)
2021-05-28 20:36:05 git.cmd DEBUG Popen(['git', 'pull'], cwd=C:\Users\jenkinsuser\.mussels\cookbooks\clamav, universal_newlines=False, shell=None, istream=None)
PS C:\Users\jenkinsuser\tmp>