Import of RT #552

jch <Juliusz.Chroboczek@pps.jussieu.fr> 2005-10-13
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The functions get_matcher and get_before_matcher are not smart enough
about checkpoints. They unconditionally grab a pristine tree (which
might or might not involve patching from the latest checkpoint,
depending on the repo format) and then patch backwards from there.

Instead, they should fetch the checkpoint that's closest to the point
requested, and patch forwards or backwards from there.

We need an interface in the repository interface to find out which
checkpoints are available and pull them out of the repo. In order to
be efficient with Git repos (in the current mapping, David), this
interface should not require that a checkpoint be associated with a
tag.

Ideas for such welcome.

Juliusz