Re: Hmm.. Try harder to find the common commits in git protocol?

Linus Torvalds [off-list ref] writes:

Hmm. Trying to debug this, I find the behavior hard to reproduce. But I 
*also* find that there seems to be something wrong in builtin-fetch-pack.

Look at commit f3ec549481827b10609a43bf504517a0e8063a12 ("fetch-pack: 
check parse_commit/object results"), and tell me that the "parents" 
handling isn't totally broken. In particular, get_rev() does:

	struct commit_list *parents = NULL;
	..
	commit = rev_list->item;
	if (!(commit->object.parsed))
		if (!parse_commit(commit))
			parents = commit->parents;
	..

which means that "parents" will never even get set if the commit was 
already parsed!

And whether it got parsed or not depends on how we got there etc, so this 
may explain the occasionally odd behaviour I saw.

Basically, I don't think that code can be right,...

This patch should fix that problem, but I wonder why it got rewritten that 
way in the first place?

Sorry, my fault while reviewing the series.  The intent of the update was
too focused on not touching possibly bad data (i.e. when parse_commit()
does not return zero to indicate success) and failed to make sure that it
acts identically on good data --- very bad.