allow re-importing the same module from different owners

[stevengj]

Fixes #28190.

[vtjnash]

If it works, it seems like it should be correct. But maybe should also test the ->deprecated flag, and see if we can clear that? (hopefully making is possible to type Profile; using Profile, although the error message that prints currently is different)

[stevengj]

Profile; using Profile works for me with no error (but a depwarn for the first statement), so I'm not sure what checking the deprecated flag would accomplish here?

[vtjnash]

I get:

julia> Profile; using Profile
WARNING: Base.Profile is deprecated, run `using Profile` instead
 in module Main
ERROR: importing Profile into Main conflicts with an existing identifier

But then every subsequent usage still gives:

julia> Profile 
WARNING: Base.Profile is deprecated, run `using Profile` instead
 in module Main
Profile

[stevengj]

With this PR?

[vtjnash]

No, before the PR. Does this fix it?

[stevengj]

@vtjnash, I now get

julia> Profile
WARNING: Base.Profile is deprecated, run `using Profile` instead
 in module Main
Profile

julia> using Profile

julia> Profile
WARNING: Base.Profile is deprecated, run `using Profile` instead
 in module Main
Profile

i.e. it doesn't give an error any more, but it doesn't clear the deprecated flag. I'm not certain under what conditions on import it would be correct to clear it, though.

[stevengj]

I'll go ahead and merge this as it seems uncontroversial … additional changes to clear the deprecation flag can go into a separate PR.