Me too!.. (as you can see from the commands below, I am on Windows)…
C:\Users\Rosdi\Projects\BlankCordovaApp1\BlankCordovaApp1\BlankCordovaApp1 [master +2 ~0 -0 !]> ionic lib update
Unable to load ionic lib version information
Are you sure you want to replace C:\Users\Rosdi\Projects\BlankCordovaApp1\BlankCordovaApp1\BlankCordovaApp1\www\lib\ionic with an updated version of Ionic?
(yes/no): yes
Latest version: 1.2.1 (released 2015-12-18)
Downloading: https://github.com/driftyco/ionic-bower/archive/v1.2.1.zip
[=============================] 100% 0.0s
Invalid version: 1.2.1
C:\Users\Rosdi\Projects\BlankCordovaApp1\BlankCordovaApp1\BlankCordovaApp1 [master +2 ~0 -0 !]>