shelve: teach new shelf class to check if .shelve file exists
This removes the only remaining use for `shelvedfile`, so the class
now goes away.
Differential Revision: https://phab.mercurial-scm.org/D9713
Do not strip innocent children. See https://bitbucket.org/facebook/hg-experimental/issues/6/hg-absorb-merges-diverged-commits
$ cat >> $HGRCPATH << EOF
> [extensions]
> absorb=
> drawdag=$TESTDIR/drawdag.py
> EOF
$ hg init
$ hg debugdrawdag << EOF
> E
> |
> D F
> |/
> C
> |
> B
> |
> A
> EOF
$ hg up E -q
$ echo 1 >> B
$ echo 2 >> D
$ hg absorb -a
warning: orphaned descendants detected, not stripping 112478962961, 26805aba1e60
saved backup bundle to * (glob)
2 of 2 chunk(s) applied
$ hg log -G -T '{desc}'
@ E
|
o D
|
o C
|
o B
|
| o F
| |
| o C
| |
| o B
|/
o A