absorb: preserve changesets which were already empty
Most commands in Mercurial (commit, rebase, absorb itself) don’t create empty
changesets or drop them if they become empty. If there’s a changeset that’s
empty, it must be a deliberate choice of the user. At least it shouldn’t be
absorb’s responsibility to prune them. The fact that changesets that became
empty during absorb are pruned, is unaffected by this.
This case was found while writing patches which make it possible to configure
absorb and rebase to not drop empty changesets. Even without having such config
set, I think it’s valuable to preserve changesets which were already empty.
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Test file dedicated to checking side-data related behavior
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Check data can be written/read from sidedata
============================================
$ cat << EOF >> $HGRCPATH
> [extensions]
> testsidedata=$TESTDIR/testlib/ext-sidedata.py
> EOF
$ hg init test-sidedata --config format.exp-use-side-data=yes
$ cd test-sidedata
$ echo aaa > a
$ hg add a
$ hg commit -m a --traceback
$ echo aaa > b
$ hg add b
$ hg commit -m b
$ echo xxx >> a
$ hg commit -m aa
$ hg debugsidedata -c 0
2 sidedata entries
entry-0001 size 4
entry-0002 size 32
$ hg debugsidedata -c 1 -v
2 sidedata entries
entry-0001 size 4
'\x00\x00\x006'
entry-0002 size 32
'\x98\t\xf9\xc4v\xf0\xc5P\x90\xf7wRf\xe8\xe27e\xfc\xc1\x93\xa4\x96\xd0\x1d\x97\xaaG\x1d\xd7t\xfa\xde'
$ hg debugsidedata -m 2
2 sidedata entries
entry-0001 size 4
entry-0002 size 32
$ hg debugsidedata a 1
2 sidedata entries
entry-0001 size 4
entry-0002 size 32
Check upgrade behavior
======================
Right now, sidedata has not upgrade support
Check that we can upgrade to sidedata
-------------------------------------
$ hg init up-no-side-data --config format.exp-use-side-data=no
$ hg debugformat -v -R up-no-side-data
format-variant repo config default
fncache: yes yes yes
dotencode: yes yes yes
generaldelta: yes yes yes
sparserevlog: yes yes yes
sidedata: no no no
persistent-nodemap: no no no
copies-sdc: no no no
plain-cl-delta: yes yes yes
compression: zlib zlib zlib
compression-level: default default default
$ hg debugformat -v -R up-no-side-data --config format.exp-use-side-data=yes
format-variant repo config default
fncache: yes yes yes
dotencode: yes yes yes
generaldelta: yes yes yes
sparserevlog: yes yes yes
sidedata: no yes no
persistent-nodemap: no no no
copies-sdc: no no no
plain-cl-delta: yes yes yes
compression: zlib zlib zlib
compression-level: default default default
$ hg debugupgraderepo -R up-no-side-data --config format.exp-use-side-data=yes > /dev/null
Check that we can downgrade from sidedata
-----------------------------------------
$ hg init up-side-data --config format.exp-use-side-data=yes
$ hg debugformat -v -R up-side-data
format-variant repo config default
fncache: yes yes yes
dotencode: yes yes yes
generaldelta: yes yes yes
sparserevlog: yes yes yes
sidedata: yes no no
persistent-nodemap: no no no
copies-sdc: no no no
plain-cl-delta: yes yes yes
compression: zlib zlib zlib
compression-level: default default default
$ hg debugformat -v -R up-side-data --config format.exp-use-side-data=no
format-variant repo config default
fncache: yes yes yes
dotencode: yes yes yes
generaldelta: yes yes yes
sparserevlog: yes yes yes
sidedata: yes no no
persistent-nodemap: no no no
copies-sdc: no no no
plain-cl-delta: yes yes yes
compression: zlib zlib zlib
compression-level: default default default
$ hg debugupgraderepo -R up-side-data --config format.exp-use-side-data=no > /dev/null