Default PS1 missing in 3.6.0 if run through a bash script and no .singularity.d in image

[DrDaveD]

Version of Singularity:

What version of Singularity are you using?

3.6.0~rc.4-1.el7

Expected behavior

I expect to see a prompt whenever singularity invokes an interactive bash.

Actual behavior

Whenever a bash script is run, PS1 gets set to empty. If a bash script invokes singularity, and singularity invokes an interactive bash using a container sandbox image that has no .singularity.d (as many of our containers currently do because we read them with docker tools), then there is no prompt string. 3.5.3 put in a default PS1 of "Singularity> ".

Steps to reproduce this behavior

singularity build --fix-perms --sandbox centos7-sandbox docker://centos:7
rm -rf centos7-sandbox/.singularity.d
(echo '#!/bin/bash'; echo 'singularity "$@"') >dosing
chmod +x dosing
./dosing exec centos7-sandbox bash

What OS/distro are you running

CentOS 7.8

How did you install Singularity

From the EPEL scratch build

I am working around the problem by doing export PS1="${PS1:-Singularity> }" in my singularity bash script wrapper.