[repo] fix extid2entity to ensure connection's has a cnxset else we'll call source.doexec, which attempt to access to cnxset.cu, and crash in some case (eg unittest_cwxmlparser in sobjects/test). Also, manually switch to 'write' mode to ensure cnxset is not released until commit/rollback when some entity is inserted.

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sync_schema_props_perms('cw_source', syncprops=False)

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if schema['BigInt'].eid is None:

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    add_entity_type('BigInt')