GNOME versioning scheme leads to "versions are not in order"

[sophie-h]

$ appstream-util validate-relax org.gnome.Software.appdata.xml 
org.gnome.Software.appdata.xml: FAILED:
• tag-invalid           : <release> versions are not in order [40 before 40.rc]
Validation of files failed

[hughsie]

On Fedora we use librpm to do the vercmp, but on other distros we fall back to a more naive implementation. Unfortunately for rpm:

$ rpmdev-vercmp 40 40.rc
40 < 40.rc