Turns out integers are used as is in `random.seed()`, but strings are
hashed (in the version 1 protocol), and the hashing isn't stable. So
instead we hack around this by using `ord()` on each character and
concatenating the digits. Yucky, but probably better than using numpy
and putting this tool on the list of tools that inherit galaxy's
environment (or adding a requirement tag and resolving with conda ...).