/bin/echo cannot handle long lists

[Diggsey]

When the manifest is long, running /bin/echo will fail:
-bash: /bin/echo: Argument list too long

Using just echo will work presumably because it's a bash builtin, but maybe there are better ways to do this filtering? (cough rust rewrite cough)

(Also to note: this will not cause a failure, it will just result in an empty manifest!)