revlog: support reading generaldelta revlogs
Generaldelta is a new revlog global flag. When it's turned on, the base field
of each revision entry holds the deltaparent instead of the base revision of
the current delta chain.
This allows for great potential flexibility when generating deltas, as any
revision can serve as deltaparent. Previously, the deltaparent for revision r
was hardcoded to be r - 1.
The base revision of the delta chain can still be accessed as before, since it
is now computed in an iterative fashion, following the deltaparents backwards.
$ hg init
$ echo This is file a1 > a
$ echo This is file b1 > b
$ hg add a b
$ hg commit -m "commit #0"
$ echo This is file b22 > b
$ hg commit -m "comment #1"
$ hg update 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm b
$ hg commit -A -m "comment #2"
removing b
created new head
$ hg update 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg update
abort: crosses branches (merge branches or use --check to force update)
[255]
$ hg update -c
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ mv a c
In theory, we shouldn't need the "-y" below, but it prevents this test
from hanging when "hg update" erroneously prompts the user for "keep
or delete".
Should abort:
$ hg update -y 1
abort: crosses branches (merge branches or use --clean to discard changes)
[255]
$ mv c a
Should succeed:
$ hg update -y 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved