Cygwin git needs updating...
Yes, the irony of it - Cygwin source code is git-hosted, but their copy of git is version 2.7.0 without any of the fixes mentioned in the article:
https://cygwin.com/packages/x86_64/git/
Gitlab's restriction to a minimum of 2.7.3 is a little harsh when a) 2.8 will contain one of the fixes (so another raise of the min version then?) and b) Cygwin git is languishing at 2.7.0.
On a similar note, CentOS 7 git is actually way back at version 1.8.3.1 (with backported fixes) - does the latest Gitlab lock out CentOS 7 users then? One trick is to rebuild the Fedora Rawhide 2.7.3 src.rpm on CentOS 7 and use it to replace 1.8.3.1 (though it means you have to track Rawhide for updates...).