manifest: change manifestctx to not inherit from manifestdict If manifestctx inherits from manifestdict, it requires some weird logic to lazily load the dict if a piece of information is asked for. This ended up being complicated and unintuitive to use. Let's move the dict creation to .read(). This will make even more sense once we start adding readdelta() and other similar methods to manifestctx.

manifest: make uses of _mancache aware of contexts In a future patch we will change manifestctx and treemanifestctx to no longer derive from manifestdict and treemanifest, respectively. This means that consumers of the _mancache will now need to be aware of the different between the two, until we get rid of the manifest entirely and the _mancache becomes only filled with ctxs.

manifest: add treemanifestctx class Before we start using repo.manifestlog in the rest of the code base, we need to make sure that it's capable of returning treemanifests. As we add new functionality to manifestctx, we'll add it to treemanifestctx at the same time. We also comment out the manifestctx p1, p2, and linkrev fields for now, since we're not implementing them on treemanifest yet.

revset: add public function to create matcher from evaluatable tree "hg debugrevspec" will use it to evaluate unoptimized tree.

revset: make analyze() a separate step from optimize() This will allow us to evaluate unoptimized tree and compare the result with optimized one. The private _analyze() function isn't renamed since I'll add more parameters to it.

revset: extract tree transformation from optimize() This patch separates the simple tree transformation from the optimization step, which is called as _analyze() since I'll extend this function to infer ordering flags. I want to avoid making _optimize() more complicated. This will also allow us to evaluate unoptimized tree.

hghave: fix has_bzr() to not try to import RevisionSpec as module Since RevisionSpec isn't a module, "import bzrlib.revisionspec.RevisionSpec" would always raise ImportError.