Merge problems with git-mingw

Hi!

I am running the mingw port of Git from a Cygwin environment, because I had problems with the Cygwin version (not sure what the problem was, probably a CRLF issue). Everything works fine, except for merging:

  $ git merge master
  usage: git-var [-l | <variable>]
  $

Does anyone have any idea on what could cause that? (I've checked that git-var is indeed the mingw version and not the Cygwin version).

  $ git --version
  git version 1.5.3.mingw.1

I'm running on top of another version control system, so I need to switch back to master and update the sources from upstream using that system's tools, and then merge it back into my branch. Without "git merge" working, that is a bit problematic, to say the least... :-)