The behavior of the MariaDB backend has changed behavior for UUIDField
from a `CharField(32)` to an actual `uuid` type. This is not converted
automatically, which results in all writes to the affected columns to
error with a message about the data being too long. This is because the
actual tring being written is a UUID with the `-` included, resulting in
a 36 character value which can't be inserted into a 32 character column.
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