haskell-interactive-switch-back doesn't work

[codygman]

This seems to happen every time I want to switch back to the source file I'm editing from the repl.

Steps to reproduce using master:

1. Open Haskell file
2. , s b
3. , s s
4. , s S

In some previous version I actually got the error No previous buffer. quite often, but now it seems to give no errors while staying in the repl.

[d12frosted]

It looks like , s s is bound to haskell-interactive-bring, and this function doesn't work with , s S from REPL (haskell-interactive-switch-back). Instead of using , s s, use , s S, this will call haskell-interactive-switch. But this is frustrating a little bit.

[d12frosted]

Ok, changed it a bit: #3504. What do you think?

[d12frosted]

@TheBB could you, please, add haskell label here?

@codygman A little update. My previous PR seems to be wrong, so I opened new one: #3533.