wireproto: move wireproto capabilities computation in a subfunction
It will help people that need to add capabilities (in a more subtle was that
just adding some to the list) in multiple way:
1. This function returns a list, not a string. Making it easier to look at,
extend or alter the content.
2. The original capabilities function will be store in the dictionary of wire
protocol command. So extension that wrap this function also need to update
the dictionary entry.
Both wrapping and update of the dictionary entry are needed because the
`hello` wire protocol use the function itself. This is specifically sneaky for
extension writer as ssh use the `hello` command while http use the
`capabilities` command.
With this new `_capabilities` function there is one and only one obvious
place to wrap when needed.
$ hg init rep
$ cd rep
$ mkdir dir
$ touch foo dir/bar
$ hg -v addremove
adding dir/bar
adding foo
$ hg -v commit -m "add 1"
dir/bar
foo
committed changeset 0:6f7f953567a2
$ cd dir/
$ touch ../foo_2 bar_2
$ hg -v addremove
adding dir/bar_2
adding foo_2
$ hg -v commit -m "add 2"
dir/bar_2
foo_2
committed changeset 1:e65414bf35c5
$ cd ../..
$ hg init sim
$ cd sim
$ echo a > a
$ echo a >> a
$ echo a >> a
$ echo c > c
$ hg commit -Ama
adding a
adding c
$ mv a b
$ rm c
$ echo d > d
$ hg addremove -n -s 50 # issue 1696
removing a
adding b
removing c
adding d
recording removal of a as rename to b (100% similar)
$ hg addremove -s 50
removing a
adding b
removing c
adding d
recording removal of a as rename to b (100% similar)
$ hg commit -mb
$ cd ..