Code review comment for lp:~allenap/launchpad/add-rabbit-service-bug-806160

> $ make run_all &
> Assigned LPCONFIG=12345
> $ export LPCONFIG=12345
> $ make sync_branches

To me this would be unacceptable. Development is complicated enough.

Adding an extra step means another thing to remember, or another wiki
page to read, and the "Assigned LPCONFIG=12345" line would be mixed
into other log lines, or disappear off the scrollback.

Perhaps we could do something better:

- config.push() could also write out the fragments its given to
  configs/$LPCONFIG/extra-${sequence}-${name}.conf

- configs.pop() would remove the fragment from the filesystem too.

- canonical.config would automatically know to look for these extra-*
  files and push them in ${sequence} order.

- configs/*/extra-* could be added to .bzrignore

- make clean could remove them