The files $g/rebase-{merge,apply}/{head-name,msgnum,end} are not
guaranteed to exist. When attempting to cat them, squelch the error
output.
In addition to guarding against stray directories, this patch addresses
a real problem:
# on terminal 1
$ git rebase -i master
# ignore editor, and switch to terminal 2
cat: .git/rebase-merge/msgnum: No such file or directory
cat: .git/rebase-merge/end: No such file or directory
$
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>