Worth fixing bugs in external cvsps conversion? (issue1643)

[Greg Ward]

Hi all --

issue1643 reports a problem converting a CVS repository using external
cvsps.  I can reproduce the problem, and I think this crash would
happen for any CVS repository where a file was first added on a
branch, then added again on the trunk.  The bug was reported in Hg
1.2.1, and I can reproduce on current crew.  And I have a fix that
seems to work.

BUT: is this even worth fixing?  There is nothing unusual about adding
a file on a branch.  If 'convert' with external cvsps crashes on that
simple case, how many people are likely to be using it?  (Builtin
cvsps handled this case just fine.)

Perhaps we should put in a big warning when people use external cvsps
that says, "using external cvsps is deprecated and will go away in
Mercurial version X".  If we do this now, before 1.3, could X = 1.4?

Greg