[migractions] add a dropped_constraints() migration command
Example usage:
>>> with dropped_constraints('MyType', 'myattr',
... UniqueConstraint, droprequired=True):
... add_attribute('MyType', 'myattr')
... # + instructions to fill MyType.myattr column
...
>>>
[MESSAGES CONTROL]
disable-msg = C0301
[VARIABLES]
# Enable / disable this checker
enable-variables = yes
additional-builtins = _, display_name
[BASIC]
required-attributes=
attr-rgx = (w|[a-z_][a-z0-9_]{2,30})
variable-rgx = (w|[a-z_][a-z0-9_]{2,30})$
argument-rgx = (w|[a-z_][a-z0-9_]{2,30})$
[TYPECHECK]
generated-members=debug,info,notice,warning,error,critical,exception