bash declare must be in first line , docker build on Ubuntu failed

[racheliurui]

Building on aws Ubuntu server, hit 2 issues,

issue 1

## fix the [[ and warning, select No to use bash instead of sh
sudo dpkg-reconfigure dash

issue 2

/root/ros_install.sh: 23: /root/ros_install.sh: Syntax error: "(" unexpected

After check, found the copy right declaration occupied the first line of bash declaration.
This will make the #!/bin/bash declaration invalid.
After change the sequence, solved the problem.

aws-builders-fair-projects/reinvent-2019/lego-ev3-raspberry-pi-robot/docker/ev3dev/ros_install.sh

Line 15 in 3121dcb

#!/bin/bash