checkheads: check successors for new heads in both missing and common
A relevant obsolete marker may have been added -after- we previously
exchanged the changeset. We have to search for remote heads that
disappear by the sole fact of pushing obsolescence.
This case will also happen when remote got the new version from a
repository that does not propagate obsolescence markers.
checkheads: attend to phases when computing new heads with obsolete
Checkheads was more permissive than expected. When the remote heads
are public we don't need to search for successors. None will make a
public head disappear.
test: add testing of checkheads behavior with obsolete
Expected behavior is quite complex. Explicit testing with clear
scenarios is welcome.
i18n-pt_BR: synchronized with
f5e86b416e05