fails on backslash escape inside backquotes
Here is a quite small example:
echo echo "\\""
The main shell invocation replaces \ by , then the subshell (created by the backquotes) replaces " by ". The effect of executing this script is that a " character, followed by newline, is written on stdout.
Morbig says: Fatal error: exception Failure("Unterminated nesting.")
This example is also in tests/good/2.6-word-expansions/2.6.3-command-substitutions