Describe the bug

Testing \s([^\s\[]+)(?:\[(\d+)\])?:\s against this input:

Nov 11 21:03:26 abc2 def.sh[1]: 
Nov 11 21:03:26 abc2 def.sh: 

It shows no match.

What happened?

It seems the regex tester fails with the second line for some reason:

• Without the second line, it can match the first line Nov 11 21:03:26 abc2 def.sh[1]: , which is correct.
• With the second line, it shows no match at all (even no match for the first line).

Expected output (try https://regex101.com/ for example): 2 matches (the [1] part is optional in the regex)

System information

Firefox

Where did you encounter the bug?

A self hosted