Trying to do a better guessing for locales in posix #884, #886

@kwpolska : can you test in your side before merging ?
We have tree reports of working fine and  Travis is green but In some cases it sets in the environment 
LC_ALL <- LC_TIME
and I remember the attempt to change in nikola code LC_ALL - > LC_TIME code give you problems.

If it is ok to merge, then it would be desirable to do a 6.2.1 release.