Docker run uses SH to run the .bbrun.sh script causing source commands to fail

[vijayakumark]

Current Behaviour:
When the --interactive flag is passed, the container is run with /bin/bash. However in the course of a normal pipeline run, sh is used though the .bbrun.sh file has it's first line pointing to bash via #!/usr/bin/env bash.
This causes bash specific features like the source command that's used to run a script that doesn't have executable permission to fail (like source venv/bin/activate that's common in python projects)

Expected Behaviour:
Since we already use /bin/bash in the interactive shell, we could use /bin/bash for non-interactive mode script execution as well.