RC2 comes before alpha5 in terms of semver #191
Description
Semver compares prelease version in ASCII. Turns out RC is smaller than alpha. With http://semver.npmjs.com/ you can see that writing a range like ~2.0.0-RC2 selects RC2 and alpha 1 to 5.
Just changing the label to rc in lowercase would fix it.
http://semver.org/#spec-item-11
When major, minor, and patch are equal, a pre-release version has lower precedence than a normal version. Example: 1.0.0-alpha < 1.0.0. Precedence for two pre-release versions with the same major, minor, and patch version MUST be determined by comparing each dot separated identifier from left to right until a difference is found as follows: identifiers consisting of only digits are compared numerically and identifiers with letters or hyphens are compared lexically in ASCII sort order.