phases: use revision number in `_pushdiscoveryphase`
We now reach our target checkpoint in terms of rev-num conversion. The
`_pushdiscoveryphase` function is now performing graph computation based on
revision number only. Avoiding repeated conversion from node-id to rev-num.
See previous changeset updated `new_heads` for rationnal.
Again, time saved in the 100 milliseconds order of magnitude for the mozilla-try
benchmark I have been using.
However, wow that the logic is done using revision number, we can look into having
better logic in the next changesets, which will provide a much bigger speedup.
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
end_of_line = lf
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true
end_of_line = lf
[*.t]
indent_size = 2
indent_style = space
trim_trailing_whitespace = false
end_of_line = lf