Follow-up to the two cherry-picked contributor commits.
The picked fence tracker never checked for a closing fence once a block was
open (the closer test sat inside the not-in-code branch), so every prose link
after any code block was scanned verbatim again and the #111254 documentation
link exemption was lost; a fence line carrying an info string was also accepted
as a closer, which handed the scanner back to prose mode mid-block. Rewrite the
loop around CommonMark fence semantics: a block opens on 3+ backticks/tildes
indented at most 3 spaces (backtick info strings may not contain a backtick)
and closes only on a fence with the same marker, at least as long, and nothing
after it; tab- or 4-space-indented lines are code; an unclosed fence stays
code to EOF. plugin_guard inherits the behaviour through scan_file.
The temp-root exemption in destructive_root_rm now also refuses a parent
segment reached through an empty path segment or followed by a shell
separator, which the first cut let through.
Tests trimmed to one invariant per fix: the fence test covers the six code
shapes plus the prose-link-after-fence control that the picked version broke;
the rm test gains the two residual shapes.
Part of #111334Fixes#112129Fixes#111335
teknium1
33292affd6