Merge branch 'mm/mv-file-to-no-such-dir-with-slash' into maint

"git mv A B/", when B does not exist as a directory, should error
out, but it didn't.

* mm/mv-file-to-no-such-dir-with-slash:
  mv: let 'git mv file no-such-dir/' error out on Windows, too
  mv: let 'git mv file no-such-dir/' error out