Vague error message for 0.0.0-pre

[bnickel]

This looks like an edge case but I struggled to diagnose it for a few hours.

My podspec looks like this:

Pod::Spec.new do |s|
  s.name = 'MyLib'
  s.version = '0.0.0-alpha.0'
  ...

When I run pod spec lint MyLib.podspec, I get the following error, produced by Molinillo:

    - ERROR | [iOS] unknown: Encountered an unknown error (CocoaPods could not find compatible versions for pod "MyLib":
  In Podfile:
    MyLib (from `/Users/bnickel/Documents/GitHub/my-lib/MyLib.podspec`)

After some experimentation, I discovered that any pre-release label on 0.0.0 triggers this error. Validation continues if I use 0.0.0 or 0.0.1-alpha.0. This could either be resolved by adding support for 0.0.0 pre-releases or improving the message that gets logged in this case.