+sub make_commit ($$) {
+ my ($parents, $message_paras) = @_;
+ my $tree = cmdoutput qw(git write-tree);
+ my @cmd = (qw(git commit-tree), $tree);
+ push @cmd, qw(-p), $_ foreach @$parents;
+ push @cmd, qw(-m), $_ foreach @$message_paras;
+ return cmdoutput @cmd;
+}
+
+sub hash_commit ($) {
+ my ($file) = @_;
+ return cmdoutput qw(git hash-object -w -t commit), $file;
+}
+
+sub hash_commit_text ($) {