Unpredictable Regex behavior in TSG

[nohehf]

As observed in: github/stack-graphs#437 (comment) It seems some regexes are not behaving exactly as their rust counter part.

For instance, in rust the regular expression: ".[^\.\\/]+$" (designed to match the file extension on a path) applied to ./bar wont match (as expected). However in tsg, it will match /bar:

scan "./bar" {
    "\.[^\.\\/]+$" {
      print $0
    }
 }
; execution prints /bar

Note: I did not dig more into the root cause or other inconstancies / minimal reproduction as of now, this is just the exact bug I encountered.

(fyi @hendrikvanantwerpen I'm creating this issue as a follow up to this discussion: github/stack-graphs#439)