Today was a nice reminder that there are no end of bugs lurking in filename
handling code. 

First, fixed a bug that prevented git-annex from adding
filenames starting with ":", because that is a special character to git.

Second, discovered that git 1.8.4 rc0 has changed `git-cat-file --batch` in
a way that makes it impossible to operate on filenames containing spaces.
This is, IMHO, a reversion, so hopefully my
[bug report](http://bugs.debian.org/718517) will get it fixed.

Put in a workaround for that, although using the broken version of git
with a direct mode repository with lots of spaces in file or directory
names is going to really slow down git-annex, since it often has to fork a
new git cat-file process for each file.

Release day tomorrow..
