Rejects valid code with type-bound assignment

[Janus Weil]

Hi Andrew,

> $ gfortran -c 4531.F90 -o 4531.o
> 4531.F90:5.34:
>
>      generic   :: assignment(=) => assign
>                                   1
> Error: Entity 'nca' at (1) is already present in the interface
>
> The test case was reduced from a much larger module using delta. The "ncb"
> type and the "tis => bf" binding seems to be necessary to trigger the problem.
>
> I can't find anything which appears to be related on bugzilla. I'll go ahead
> and file a PR unless someone can point out an existing one.

this is certainly very similar to PR 54195. The test case there is
slightly different, but I think both  are regressions of the same
commit of mine. I added your test case there as comment 8.

Thanks for reporting,
Janus