Split commit naming

[Joseph Myers]

I'm testing a gcc-conversion patch to implement the branchpoint fixes I 
identified for GCC branches where cvs2svn chose a bad parent for the 
branch-creation commit.

With that patch, I see:

# /branches/gcc-3_4-rhl-branch
<80870>|<81014> reparent --use-order
reposurgeon: couldn't match a name at <80870>

And indeed, the relevant commit has "Legacy-ID: 80870.2" as a "[[Split 
portion of a mixed commit.]]" (where the SVN commit changed both 
gcc-3_3-branch and gcc-3_4-branch).

My question is: is it a stable interface to reposurgeon that the portions 
of such a split commit will always be numbered in lexicographical order by 
branch name (or some other such well-defined stable ordering), so I can 
write <80870.2> in gcc.lift and know that some reposurgeon change won't 
accidentally make that refer to the portion of the commit on 
gcc-3_3-branch instead?

-- 
Joseph S. Myers
joseph@codesourcery.com