changegroup3: introduce experimental.changegroup3 boolean config
In order to give us the freedom to change the changegroup3 format,
let's hide it behind an experimental config. Since it is required by
treemanifests, that will override the cg3 config.
$ hg init a
$ cd a
$ hg init b
$ echo x > b/x
Should print nothing:
$ hg add b
$ hg st
$ echo y > b/y
$ hg st
Should fail:
$ hg st b/x
abort: path 'b/x' is inside nested repo 'b' (glob)
[255]
$ hg add b/x
abort: path 'b/x' is inside nested repo 'b' (glob)
[255]
Should fail:
$ hg add b b/x
abort: path 'b/x' is inside nested repo 'b' (glob)
[255]
$ hg st
Should arguably print nothing:
$ hg st b
$ echo a > a
$ hg ci -Ama a
Should fail:
$ hg mv a b
abort: path 'b/a' is inside nested repo 'b' (glob)
[255]
$ hg st
$ cd ..