log: slowpath: only walk specified revision range during preparation
Even with --removed, it does not make sense to examine changesets outside
of the revision range that was specified by the user: the last phase only
yields a subset of (revs), preparation phase hence only has to examine
(revs) to fill correctly fncache.
% test multiple merges at once
initializing destination source-hg repository
scanning source...
sorting...
converting...
4 Initial add
3 Added branch1 file
2 Added parent file
1 Added brach2 file
0 Merged branches
o 5 "(octopus merge fixup)" files:
|\
| o 4 "Merged branches" files: file-branch2
| |\
o---+ 3 "Added brach2 file" files: file-branch2
/ /
| o 2 "Added parent file" files: file-parent
| |
o | 1 "Added branch1 file" files: file file-branch1
|/
o 0 "Initial add" files: file
% manifest of tip
644 file
644 file-branch1
644 file-branch2
644 file-parent