[PATCH][gdb/testsuite] Handle PS1 quirk in gdb.base/multi-line-starts-subshell.exp

[Tom de Vries]

On 12/14/20 4:47 PM, Tom Tromey wrote:
>>>>>> "Tom" == Tom de Vries <tdevries@suse.de> writes:
> 
> Tom> The problem is that the PS1 setting has no effect.
> 
> Why is that?
> 

The mechanism is as follows:
- /etc/profile sets ENV=/etc/bash.bashrc
- /bin/sh is started
- /bin/sh executes ENV, in other words /etc/bash.bashrc
- during the execution of /etc/bash.bashrc, PS1 is set unconditionally

AFAIU, this is caused by this PR (
https://bugzilla.opensuse.org/show_bug.cgi?id=611966 ) which lurks in
older version of openSUSE/SUSE.

> Tom> Fix this by setting PS1 after spawning the subshell.
> 
> Tom> Tested on x86_64-linux.
> 
> Tom> Any comments?
> 
> It seems fine but it may be good to understand why it is needed and
> perhaps add a comment explaining it.

Ack, will do.

Thanks,
- Tom