The obsolete._enabled flag has become a config option. This updates all but one
of the tests to use the minimal number of flags necessary for them to pass. For
most tests this is just 'createmarkers', for a couple tests it's
'allowunstable', and for even fewer it's 'exchange'.
"use push -f to force" in the hint at abortion of "hg push" may cause
novice users to execute "push -f" easily without understanding about
problems of multiple branch heads in the repository.
This patch hides description about "-f" in the hint, and leads into
seeing "hg help push" for details about pushing new heads.
This applies the same logic as used for `obsolete` and `unstable` changesets.
Refuse to push them without force.
We'll probably want to factor this logic with two new functions
`pctx.troubled()` and `ctx.troubles()`. But I'm waiting for the third
"trouble" to make it into core.
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 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.
