Got it!!
Thank you @Benjamin_D , and @Andrew Schleifer !!
Indeed what I tested is after I removed the parts below, it could work well without any error, but the entire plugins would not be installed.
- sudo -E -u discourse git clone https://github.com/discourse/discourse-solved.git
- sudo -E -u discourse git clone https://github.com/discourse/discourse-checklist.git
- sudo -E -u discourse git clone https://github.com/discourse/discourse-whos-online.git
- sudo -E -u discourse git clone https://github.com/gdpelican/babble.git
- sudo -E -u discourse git clone https://github.com/kasperpeulen/discourse-mathjax.git
- sudo -E -u discourse git clone https://github.com/discourse/discourse-tooltips.git
- sudo -E -u discourse git clone https://github.com/paviliondev/discourse-topic-previews.git
- sudo -E -u discourse
Thank you for your help!!
BR,
Chieh