Parsing fails for *some* list nodes inside command substitution nodes.

[gmoshkin]

To reproduce do:

import bashlex
bashlex.parser.parse('echo $(pwd && pwd)')

Results in ParsingError: unexpected token ')' (position 10)

Parsing also fails for 'echo $(pwd || pwd)' and 'echo $(pwd & pwd)', but 'echo $(pwd ; pwd)' parses just fine.