[BUG] attribute "eol" with "crlf"

There's a bug in git-1.7.8 if you use the attribute "eol" with "crlf".

Steps to reproduce:
- add and commit a text file which uses 0d0a for line breaks
7465 7374 0d0a 0d0a 7465 7374 0d0a       test....test..
- add ".gitattributes" with "*.txt eol=crlf"
- change a line in the file
- execute "git checkout [file]"

The result is:
7465 7374 0d0d 0a0d 0d0a 7465 7374 0d0d  test......test..

0d0a was replaced by 0d0d0a.