Storage internals: UUID

[Stephen J. Turnbull]

Daniel Carrera writes:

 > Hg and Git protect the integrity of not only the tree, but also the
 > history leading up to it (assuming that you don't rebase, which I
 > think Git people do often).

Rebasing is irrelevant; you still detect the difference in history,
and it *is* a different history even if it's intended to result in the
same tree.

In git, using the reflog it would be easy and fast to verify that a
simple rebase corresponds to a given original branch history.  (Of
course if the reflog has expired, the original branch may have been
garbage-collected.)

hg also has a notion of "loose heads" that could be checked, but
without a reflog it's not obvious what heads should be compared.  I'm
also not sure under what conditions old revision data can get GC'ed in
hg.