Lowercase history table_name before checking if it exists:

[ruttenb]

We do this because the CREATE TABLE sql command is automatically lower casing table_name since it is not wrapped in double quotes. This is an issue for app labels that have upper case letters. The table_exists function is always returning false if the app has upper case letters. Then, an exception is raised when attempting to create a table with the same name.

[dcwatson]

I guess if I were writing this all over again, I'd try to make the history tables match the case of the source tables. But given that postgres automatically lowercases anyway, I think this is fine.