Comment # 3 on bug 1164553 from Michael Schr�der

rpm.vercmp is correct, your usage is wrong. rpm.vercmp just compares the
epoch/version/release part, you can't use it to compare a full EVR.

You'll need to split to string into epoch/version/release and then call
rpm.vercmp on the individual parts. But you already found that out yourself.
;-)

See also https://github.com/rpm-software-management/rpm/issues/897

Btw, your epoch match is wrong. It has to be "^([0-9]+):" instead of "^(.+):".
And no epoch match always means epoch "0".