Fix MatchError during default value parsing, ignoring more time default ...

...functions

See https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!msg/scalaquery/CvaWXZ52Ong/HpPcpt07k50J

no review

/cc @szeiger 
Who ensures that the database supports this syntax? This needs to be guarded by a capability or done with the lifted embedding.