Same problem on an old repository on Ubuntu 18.04 trying to commit a regular text file. Definitively not WebDAV in my case. Solved it by backing up, checking the file out and applying the backup over it.
-- You received this message because you are subscribed to the Google Groups "Git for human beings" group. To unsubscribe from this group and stop receiving emails from it, send an email to git-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.