[DBIx-Class-Devel] [dbsrgits/dbix-class] fix: Don't add indices on columns with UNIQUE constraint (#113)

[Marc0]

SQL::Translator::Parser::DBIx::Class adds an index to foreign key
columns as this "is normally the sensible thing to do". Agreed.

Besides SQL::Translator::Parser::DBIx::Class takes care to not add an
additional index to primary key columns ("some RDBMS croak on this, and
it generally doesn't make much sense") but doesn't consider columns with
a UNIQUE constraint where it doesn't make any sense either.

Generally this should not be dangerous but it doesn't help at all.