_sso_location sometimes returns exceptions instead of raising them #1
Description
The _sso_location method in Saml2Client (which is called by Saml2Client.authenticate) creates a IdpUnspecified exception in three places, but in two of those places, it returns the exception instead of raising it.
I tried changing it so that it raises the exception in all three cases, but that causes a test to fail in test_63_ecp.
So either the test is misconfigured and wasn't noticing because the exception was getting lost, or everything is working as expected. If that's the case, I'd suggest returning something other than an exception or otherwise indicating that this isn't a fatal error.
If the test is misconfigured and should have been failing, it should probably be updated so that it's doing more evaluation of the return value. It seems bad that an exception class could be folded into a saml object without the test noticing.