bisect-runner.pl should match patches with directory 'b' before 'a'.

The pattern to extract the file for diagnostics should a patch not apply was
failing to match (and generating a legitimate used of uninitialized value
warning) for the case where the patch was specified as --- b/ +++ a/
The pattern was only expecting --- a/ +++ b/

1 files changed, 1 insertions, 1 deletions

diff --git a/Porting/bisect-runner.pl b/Porting/bisect-runner.pl
index be88d59c56..101b036615 100755
--- a/Porting/bisect-runner.pl
+++ b/Porting/bisect-runner.pl
@@ -967,7 +967,7 @@ sub apply_patch {
     my ($patch, $what, $files) = @_;
     $what = 'patch' unless defined $what;
     unless (defined $files) {
-        $patch =~ m!^--- a/(\S+)\n\+\+\+ b/\1!sm;
+        $patch =~ m!^--- [ab]/(\S+)\n\+\+\+ [ba]/\1!sm;
         $files = " $1";
     }
     my $patch_to_use = placate_patch_prog($patch);