Depend on emacsen-common.
old-prerm will most likely fail spewing emacsen-common error message
when upgrading from previous version but this is OK. Add a custom
prerm script which recovers from the problem and notifies the user to
ignore the error message.
Signed-off-by: Modestas Vainius <modestas@vainius.eu>
quilt versioned build-depend makes no sence. The better way is to
provide a more detailed explanation in debian/README.source which
quilt version has README.source.
Signed-off-by: Modestas Vainius <modestas@vainius.eu>