Thomas Rast authored Jun 21, 2013 and Junio C Hamano committed Jun 21, 2013

2901bbe5

 (apply: free patch->{def,old,new}_name fields, 2012-03-21)
cleaned up the memory management of filenames in the patches, but
forgot that find_name_traditional() can return NULL as a way of saying
"I couldn't find a name".

That NULL unfortunately gets passed into xstrdup() next, resulting in
a segfault.  Use null_strdup() so as to safely propagate the null,
which will let us emit the correct error message.

Reported-by: DevHC on #git
Signed-off-by: Thomas Rast <trast@inf.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>