(travis) Stop auto-upgrading everything on non-clean installs

It adds little value currently and makes version-specific installs difficult
(see next commit)
(travis) Accommodate a slow mirror grrrrr
Adjust for SQLA's API change 966200cc8
Fix copy() assuming all columns are native
Make sure the me-relname-flip does not affect any error text
Yet another missed sanity check in the relcond resolver

rel/col duality is just hateful
Ensure undef_on_null_fk does not affect non-introspectable custom conds
A more robust column equality extractor

It is a mistake to reach into $ret->{condition} - it may very well be a
non-hash structure. Also replace the silly regexping with the (already
regexed out) results of the info resolver