The version number is “<tag>-<# commits after tag>-g<git hash>”
tag is the last tag in the repo, e.g. “5.1.0”
# commits after tag is the number of commits since that tag was applied
git hash is the last few digits of the head commit when the build was made.
Confusingly “Release” just means the code was built with Debug options turned off.
But, I can’t figure where the r13579 comes from, presumably added by the packaging.