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.
$ . $TESTDIR/wireprotohelpers.sh
$ hg init server
$ enablehttpv2 server
$ cd server
$ hg debugdrawdag << EOF
> H I J
> | | |
> E F G
> | |/
> C D
> |/
> B
> |
> A
> EOF
$ hg phase --force --secret J
$ hg phase --public E
$ hg log -r 'E + H + I + G + J' -T '{rev}:{node} {desc} {phase}\n'
4:78d2dca436b2f5b188ac267e29b81e07266d38fc E public
7:ae492e36b0c8339ffaf328d00b85b4525de1165e H draft
8:1d6f6b91d44aaba6d5e580bc30a9948530dbe00b I draft
6:29446d2dc5419c5f97447a8bc062e4cc328bf241 G draft
9:dec04b246d7cbb670c6689806c05ad17c835284e J secret
$ hg serve -p $HGPORT -d --pid-file hg.pid -E error.log
$ cat hg.pid > $DAEMON_PIDS
All non-secret heads returned by default
$ sendhttpv2peer << EOF
> command heads
> EOF
creating http peer for wire protocol version 2
sending heads command
response: [
b'\x1dok\x91\xd4J\xab\xa6\xd5\xe5\x80\xbc0\xa9\x94\x850\xdb\xe0\x0b',
b'\xaeI.6\xb0\xc83\x9f\xfa\xf3(\xd0\x0b\x85\xb4R]\xe1\x16^',
b')Dm-\xc5A\x9c_\x97Dz\x8b\xc0b\xe4\xcc2\x8b\xf2A'
]
Requesting just the public heads works
$ sendhttpv2peer << EOF
> command heads
> publiconly 1
> EOF
creating http peer for wire protocol version 2
sending heads command
response: [
b'x\xd2\xdc\xa46\xb2\xf5\xb1\x88\xac&~)\xb8\x1e\x07&m8\xfc'
]
$ cat error.log