util: enhance `nullcontextmanager` to be able to return __enter__ result
This makes its functionality and signature equivalent to Python 3.7’s
contextlib.nullcontext().
#testcases continuecommand continueflag
Test rebase --continue with rebasestate written by legacy client
$ cat >> $HGRCPATH <<EOF
> [extensions]
> rebase=
> drawdag=$TESTDIR/drawdag.py
> EOF
#if continueflag
$ cat >> $HGRCPATH <<EOF
> [alias]
> continue = rebase --continue
> EOF
#endif
$ hg init
$ hg debugdrawdag <<'EOF'
> D H
> | |
> C G
> | |
> B F
> | |
> Z A E
> \|/
> R
> EOF
$ for r in A B C D E F G H R Z
> do
> eval node_$r=$(hg log -r $r -T '{node}')
> done
rebasestate generated by a legacy client running "hg rebase -r B+D+E+G+H -d Z"
$ touch .hg/last-message.txt
$ cat > .hg/rebasestate <<EOF
> 0000000000000000000000000000000000000000
> $node_Z
> 0000000000000000000000000000000000000000
> 0
> 0
> 0
>
> $node_A:-2
> $node_E:0000000000000000000000000000000000000000
> $node_B:0000000000000000000000000000000000000000
> $node_F:-3
> $node_C:-3
> $node_G:0000000000000000000000000000000000000000
> $node_D:0000000000000000000000000000000000000000
> $node_H:0000000000000000000000000000000000000000
> EOF
#if continuecommand
$ hg continue --dry-run
rebase in progress, will be resumed
#endif
$ hg continue
rebasing 4:c1e6b162678d "B" (B)
rebasing 8:6f7a236de685 "D" (D)
rebasing 2:de008c61a447 "E" (E)
rebasing 7:d2fa1c02b240 "G" (G)
rebasing 9:6582e6951a9c "H" (H tip)
warning: orphaned descendants detected, not stripping c1e6b162678d, de008c61a447
saved backup bundle to $TESTTMP/.hg/strip-backup/6f7a236de685-9880a3dc-rebase.hg
$ hg log -G -T '{rev}:{node|short} {desc}\n'
o 11:721b8da0a708 H
|
o 10:9d65695ec3c2 G
|
o 9:21c8397a5d68 E
|
| o 8:fc52970345e8 D
| |
| o 7:eac96551b107 B
|/
| o 6:bd5548558fcf C
| |
| | o 5:aeba276fcb7d F
| | |
| o | 4:c1e6b162678d B
| | |
o | | 3:f424eb6a8c01 Z
| | |
+---o 2:de008c61a447 E
| |
| o 1:21a6c4502885 A
|/
o 0:b41ce7760717 R