Use isinstance() instead of type comparison

Unused imports

[py3k] tuple unpacking in function args

[py3k] ur'' is gone

[py3k] octals and long

[py3k] Fix raise with embedded traceback python 3 removed the raise syntax with 2 and 3 expressions.

[py3k] print function

[py3k] except as

[py3k] backtick to repr

[hooks/syncschema] make sure CWUniqueTogetherConstraintDelOp happens before CWConstraintDelOp SQLServer refuses to index an unlimited text column, so we should drop unique_together constraints (which imply an index) before we drop size constraints. Closes #5560601.