revert: extract actual revert in its own function
With this small refactoring, the computation of the action to perform and the
actual change to the disk happen in different function. This allows extension to
wrap the later in case of need. The initial motivation is the `remotefilelog`
extension that need to prefetch all the file content to be checked out.
Check whether size of generaldelta revlog is not bigger than its
regular equivalent. Test would fail if generaldelta was naive
implementation of parentdelta: third manifest revision would be fully
inserted due to big distance from its paren revision (zero).
$ hg init repo
$ cd repo
$ echo foo > foo
$ echo bar > bar
$ hg commit -q -Am boo
$ hg clone --pull . ../gdrepo -q --config format.generaldelta=yes
$ for r in 1 2 3; do
> echo $r > foo
> hg commit -q -m $r
> hg up -q -r 0
> hg pull . -q -r $r -R ../gdrepo
> done
$ cd ..
>>> import os
>>> regsize = os.stat("repo/.hg/store/00manifest.i").st_size
>>> gdsize = os.stat("gdrepo/.hg/store/00manifest.i").st_size
>>> if regsize < gdsize:
... print 'generaldata increased size of manifest'