svn patch removes an EOL after a context line

If the final context line in a patch does not have an EOL, but the target file
*does* have one at that position, svn patch removes that EOL from the target file.

I added an XFail test, patch_tests.py 46, in r1443815.

See dev@ email thread "svn patch removes an EOL after a context line", started
2013-02-07, e.g. <http://svn.haxx.se/dev/archive-2013-02/0120.shtml>.