Conflicts:
	lib/sqlalchemy/orm/mapper.py

query being generated would produce a "columns being replaced"
warning for a statement with two same-named columns,
as the internal SELECT wouldn't have use_labels set.

This enables the subquery eager loader strategy to apply a DISTINCT
to the innermost SELECT subquery, to assist in the case where
duplicate rows are generated by the innermost query which corresponds
to this relationship (there's not yet a general solution to the issue
of dupe rows within subquery eager loading, however, when joins outside
of the innermost subquery produce dupes).  When the flag
is set to ``True``, the DISTINCT is rendered unconditionally, and when
it is set to ``None``, DISTINCT is rendered if the innermost relationship
targets columns that do not comprise a full primary key.
The option defaults to False in 0.8 (e.g. off by default in all cases),
None in 0.9 (e.g. automatic by default).   Thanks to Alexander Koval
for help with this. [ticket:2836]

Conflicts:
	lib/sqlalchemy/orm/relationships.py

Conflicts:
	doc/build/changelog/changelog_09.rst

- add the RETURNING glossary entry
- other "seealso's" fixed
- add doc for eager_defaults option

Fixed two typos.

- use a simple isinstance() check instead of looking for presence of
"primary_entity" flag, that's a little unclear