Subject: Re: VCS comparison table

From: Junio C Hamano <[email-masked]>
Date: Thu, 26 Oct 2006 02:33:08 -0700

"James Henstridge" <[email-masked]> writes:

> Can you really just rely on equal revision IDs meaning you have the
> same code though?

If you two have the same commit that is a guarantee that you two
have identical trees.  The reverse is not true as logic 101
would teach ;-).

Doing fast-forward instead of doing a "useless" merges helps
somewhat but not in cases like two people merging the same
branches the same way or two people applying the same patch on
top of the same commit.  You need to compare tree object IDs for
that.

>> In bzr, the only answer I'm hearing is attempting a merge to see if it
>> introduces any changes. (I'm deliberately avoiding "pull" since we're
>> talking about distributed cases here).
>
> Or run "bzr missing".  If the sole missing revision is a merge (and
> not the revisions introduced by the merge), you could assume that you
> have the same tree state.

Is it "you could assume" or "it is guaranteed"?  If former, what
kind of corner cases could invalidate that assumption?