remote-testsvn: fix unitialized variable

remote-testsvn: fix unitialized variable

In remote-test-svn, there is a parse_rev_note function to
parse lines of the form "Revision-number" from notes. If it
finds such a line and parses it, it returns 0, copying the
value into a "struct rev_note". If it finds an entry that is
garbled or out of range, it returns -1 to signal an error.

However, if it does not find any "Revision-number" line at
all, it returns success but does not put anything into the
rev_note. So upon a successful return, the rev_note may or
may not be initialized, and the caller has no way of
knowing.

gcc does not usually catch the use of the unitialized
variable because the conditional assignment happens in a
separate function from the point of use. However, when
compiling with -O3, gcc will inline parse_rev_note and
notice the problem.

We can fix it by returning "-1" when no note is found (so on
a zero return, we always found a valid value).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>