The OnClauseSpec required Task names to be \w+ or [a-zA-Z0-9_]
which is not enforced by the DSL, so it was possible to have
valid task names that could not be referenced in an on-clause.
YAML enforces some restrictions on characters in task names (#, !, |)
but other than that any JSON-schema valid string should be a valid Task
name
Change-Id: I3f1056cad7c67e160a082c2a0de2e3bfd476bc63
Closes-Bug: 1797439
e98614cd60