message: In 'branch-history', handle a couple of less common mode strings
  when parsing merge commits. Also, when the checks for a branch fail,
  print the name of the failed branch.
diff: @@ -154,7 +154,13 @@ foreach my $sha (@commits) {
  my $sz1 = int(`git diff -U0 --binary $src1 $dst | gzip -c | wc -c`);
  my $sz2 = int(`git diff -U0 --binary $src2 $dst | gzip -c | wc -c`);
  $blob_size += $sz1 < $sz2 ? $sz1 : $sz2; }
  - else { die "Unknown git status letter: $mode." }
  + elsif ($mode eq "AM") {
  + my $sz2 = int(`git diff -U0 --binary $src2 $dst | gzip -c | wc -c`);
  + $blob_size += $sz2; }
  + elsif ($mode eq "MA") {
  + my $sz1 = int(`git diff -U0 --binary $src1 $dst | gzip -c | wc -c`);
  + $blob_size += $sz1; }
  + else { die "Unknown git status letter: $mode, commit: $sha, file: $fname.\n\t" }
  }
  if ($blob_size > $max_blob_kb*1024) {
  @@ -178,6 +184,7 @@ if ($total_size > $max_branch_kb*1024) {
  }
  if ($status) {
  + printf STDERR "\033[36mBranch $branch has errors.\033[0m\n";
  chdir $cur_dir;
  my $testname = basename $0;
  open(my $f, '>', "$testname.msg");
  