>0.0.0-a does not match pre-releases on 0.0.0 that start with a
capital letter or number. This has to do with the ordering of
code points. Numbers and capital letters come before lowercase
letters.

>0.0.0-0 should match all valid pre-releases on 0.0.0. According
to the spec, "Numeric identifiers MUST NOT include leading zeroes."
A 0 is also the lowest code point for all the allowed characters
in a pre-release