bug#46466: 28.0.50; Tramp hangs with bad prompt even when using /bin/sh

[Michael Albinus <michael.albinus@gmx.de>]

Erik Hetzner <egh@e6h.org> writes:

> Hello,

Hi Erik,

> 1. Create a new user: `adduser test`
> 2. `sudo su test` and ensure that home directory is completely empty
> 3. `echo PS1=badprompt > .bash_profile
> 4. Switch back to main user
> 5. Start emacs with emacs -q
> 6. C-x C-f /ssh:test@localhost:
>
> Expected result: dired for test user home dir.
>
> Actual result: tramp hangs.
>
> This kind of issue is well documented on the internet (stackexchange,
> etc.) but I haven't seen a bug for it.
>
> As I understand it, because `tramp-default-remote-shell' is set to
> /bin/sh, tramp should ignore `.bash_profile`. When I look at running
> shells, all I see is /bin/sh, so it's not clear to me where/why/how
> /bin/bash is being invoked.

What is /bin/sh, both locally and remote? In my case, running Fedora 33,
I see

--8<---------------cut here---------------start------------->8---
# ls -l /bin/sh
lrwxrwxrwx. 1 root root 4 Jul 27  2020 /bin/sh -> bash
--8<---------------cut here---------------end--------------->8---

> Thank you!
>
> best, Erik Hetzner

Best regards, Michael.