Fix multiline string syntax highlighting when opener and closer are identical

[tminor]

7c9961b adds a test illustrating what the subject refers to.

[Mrngilles]

Changing the jsonnet-multiline-string-beg-regexp should do it. It seems to work locally, but I have not extensively tested it yet.
https://github.com/tminor/jsonnet-mode/blob/main/jsonnet-mode.el#L188

  (defconst jsonnet-multiline-string-beg-regexp "\\(|||\\)[[:space:]]*\n"))

[Mrngilles]

Seems there still is an issue there.
For now, a quick fix in code is to put the beginning ||| on a line of their own

[tminor]

Apologies for the delay.

I flailed at this quite a bit many months ago and recall having similar "here's a fix" moments but none completely alleviated the issue. IIRC (and I may very well not), a multi line string delimited by ^\s*|||$ (i.e. ||| alone on a line) at its beginning and end was the root of the issue.

[Mrngilles]

No worries.

One workaround I found was to have the opening ||| on a separate line, and I don't get any issues