So I managed to corrupt a copy of some code I checked out of my subversion repository. The error I'd get was:
Transmitting file data .svn: Commit failed (details follow):
svn: Base checksum mismatch on '/site_local/themes/collabinvest/homepage.tmpl':
svn: Your commit message was left in a temporary file:
To "work around" this problem commit the individual files and/or directories that work. Copy the files that error out to another directory.
Check out a clean copy of your code into another directory. Copy over the files that would not commit into the new checked out version. Recommit. It should work.