If the stagings are going to be created locally (via a git working
copy rather than the github API), the mergebot part needs to have
access to the cache, so move the cache over. Also move the maintenance
cron.
In an extermely minor way, this prefigures the (hopeful) eventual
merging of the ~~planes~~ modules.
Currently, if a PR forward-port PR gets detached the reason for it is
not always obvious, and may have to be hunted in the logs or in
"sibling" PRs.
By writing a forward port reason (hopefully) ever time we detach a PR,
and displaying that reason in the form and dashboard, the
justification should be a lot more obvious.
Fixes#679
The exponential backoff offsets from the write_date of the children
PRs, however it doesn't reset, so the offsetting gets bumped up way
more than originally expected or designed if the child PRs are under
active development for some reason.
Fix this by adding a field to specifically record the date of merge of
a PR, and check that feature against the backoff offset. This should
provide more regular and reliable backoff.
Fixes#369
