dirstate-v2: no longer register the data-file during transaction
If the data file change during the transaction, we cannot truncate it.
The content of the file itself is fine as it will get backed up at the same time
as the docket.
Leaving the trailing data at the end of failed transaction is fine. The
dirstate-v2 format supports it. The dead data will simply we written over if
necessary.
$ NO_FALLBACK="env RHG_ON_UNSUPPORTED=abort"
$ cat << EOF >> $HGRCPATH
> [format]
> sparse-revlog = no
> EOF
$ hg init repo --config format.generaldelta=no --config format.usegeneraldelta=no
$ cd repo
$ (echo header; seq.py 20) > f
$ hg commit -q -Am initial
$ (echo header; seq.py 20; echo footer) > f
$ hg commit -q -Am x
$ hg update ".^"
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ (seq.py 20; echo footer) > f
$ hg commit -q -Am y
$ hg debugdeltachain f --template '{rev} {prevrev} {deltatype}\n'
0 -1 base
1 0 prev
2 1 prev
rhg works on non-generaldelta revlogs:
$ $NO_FALLBACK hg cat f -r .
1
2
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footer