packaging: modify rc detection to work with X.Yrc instead of X.Y-rc
rc detection on CentOS failed without this change,
resulting in upgrades from 4.9rc to 4.9 not working
(4.9rc was considered more recent than 4.9).
Differential Revision: https://phab.mercurial-scm.org/D5876
adding changesets
adding manifests
adding file changes
added 1 changesets with 4 changes to 4 files
new changesets d326ae2d01ee (1 drafts)
4 files updated, 0 files merged, 0 files removed, 0 files unresolved
adding changesets
adding manifests
adding file changes
added 1 changesets with 4 changes to 4 files
new changesets d326ae2d01ee (1 drafts)
4 files updated, 0 files merged, 0 files removed, 0 files unresolved