Error code 127 for bash file in machine post, but manual execution in container is successful

Build Environment
1

Tech Stack : python, django, DRF, ubuntu 14.04
I have added a bash file execution bash ./circle_dev_setup.sh in machine section’s post command.
I am getting

$ bash ./circle_dev_setup.sh
bash: ./circle_dev_setup.sh: No such file or directory

bash ./circle_dev_setup.sh returned exit code 127

Action failed: bash ./circle_circle_dev_setup.sh

So just for testing, i tried out a simple bash script :

#!/bin/bash
echo "A"

For this also, same exit status as above
So I am quite sure that there is no problem with the contents of script
The project structure looks like this:

project/
    circle.yml
    <bash_script>.sh

In circle.yml :

machine:

  pre:
    - bash ./test_circle_bash.sh
...

Can you please help me in figuring out whats the issue?
Thanks in advance