discovery: add a devel.discovery.exchange-heads
Currently all discovery start with testing local and remote heads. For analysis
purpose we make it possible to disable that initial "handshake" and start
discovery with the whole repository as undecided.
Differential Revision: https://phab.mercurial-scm.org/D9801
$ hg init repo
$ cd repo
$ touch a.html b.html c.py d.py
$ cat > frontend.sparse << EOF
> [include]
> *.html
> EOF
$ hg -q commit -A -m initial
$ echo 1 > a.html
$ echo 1 > c.py
$ hg commit -m 'commit 1'
Enable sparse profile
$ cat .hg/requires
dotencode
fncache
generaldelta
revlogv1
sparserevlog
store
testonly-simplestore (reposimplestore !)
$ hg debugsparse --config extensions.sparse= --enable-profile frontend.sparse
$ ls -A
.hg
a.html
b.html
Requirement for sparse added when sparse is enabled
$ cat .hg/requires
dotencode
exp-sparse
fncache
generaldelta
revlogv1
sparserevlog
store
testonly-simplestore (reposimplestore !)
Client without sparse enabled reacts properly
$ hg files
abort: repository is using sparse feature but sparse is not enabled; enable the "sparse" extensions to access
[255]
Requirement for sparse is removed when sparse is disabled
$ hg debugsparse --reset --config extensions.sparse=
$ cat .hg/requires
dotencode
fncache
generaldelta
revlogv1
sparserevlog
store
testonly-simplestore (reposimplestore !)
And client without sparse can access
$ hg files
a.html
b.html
c.py
d.py
frontend.sparse