…y read pref, except PRIMARY queries on secondary
Particularly, fix the description of what happens with direct connection to primary with ReadPreference.SECONDARY: it doesn't fail, it succeeds.
…erence to mongos PYTHON-448
improving warning message for URI
…nstead should just patch_all() PYTHON-435
SON equality is now order sensitive.
Comparison to another SON is order-sensitive while comparison to a regular dictionary is order-insensitive
It doesn't implement an equality check.