In d0560e5 the SemVer implementations were aligned, and the logic was
simplified a bit (or so I thought). This did however result in the
introduction of a regression, as it failed to take "simple tags" into
account.
This commit ensures both are taken into account again, and ensures it
is now covered by a proper test.
Signed-off-by: Hidde Beydals <hello@hidde.co>