Fixes: #4390
Deprecated an undocumented loader option syntax ``".*"``, which appears to
be no different than passing a single asterisk, and will emit a deprecation
warning if used. This syntax may have been intended for something but there
is currently no need for it.
The original ticket was to document the `.{WILDCARD}` (e.g. `.*`) format,
however this format does not appear to be used or needed by SQLAlchemy
and is likely not used by any projects or developers.
This PR invokes `util.warn_deprecated` to notify users this functionality
is deprecated, and directs them to the #4390 issue if they actually use it.
Assuming there are no complaints over this warning in the coming months,
this code can be removed in a future major release.
Change-Id: I665e3ac26be0a7819246a2ee56fb5a5f32980c91
(cherry picked from commit
2432d2ed0b28480c0e1004a47aa74238865105b5)