$ git pull origin master
fatal: unable to access \'https://xxxxxxxxxxxxxxx\':
error setting certificate verify locations:
CAfile: C:/Users/abc/AppData/Local/P
I got the same problem after my latest update of cygwin after installing Windows 10.
The command update-ca-trust failed during installation.
The reason seem to be that the group owner for the certificate folder was corrupt.
The somewhat drastic solution was to delete /etc/group, it turned out that cygwin is able to ask windows directly about group rights.
Solution found at http://zaunerc.blogspot.se/2016/01/cygwin-mapping-windows-sids-to-posix.html