Make EditController edit_entity method always return an eid
In cases the entity was to be created or copied, eid was None hence the method
returned None despite the dosctring says the method should always return an
eid. Now if the eid variable is None, it is assigned to the newly created
entity eid.
Closes #3593029.
[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