changegroup: don't reuse 'mfest' variable for different type We have a variable 'mfest' that's first a manifest nodeid and then a manifest. Let's make it clearer by using separate variables for the two uses.

changegroup: rename 'mf' to 'ml' to match 'cl', since it's a revlog The 'mf' variable is a manifest revlog, not a manifest, so let's rename it accordingly. We already call the changelog variable 'cl', so 'ml' seems appropriate.