bundle progress: offer best-guess deterministic progress information
This uses the same strategy as progress for pulls, estimating manifests
based on changeset count and estimating file count by files list in
each changeset.
$ mkdir t
$ cd t
$ hg init
$ echo a > a
$ hg add a
$ hg commit -m test
$ rm .hg/requires
$ hg tip
abort: index 00changelog.i unknown format 2!
[255]
$ echo indoor-pool > .hg/requires
$ hg tip
abort: requirement 'indoor-pool' not supported!
[255]