title: npm: Why is a version "0.1" invalid?
body: <p>I had to change the version of my npm app from 0.1 to 0.0.1 in order for npm not to do this. </p>
  
  <pre><code>$ npm install
  npm ERR! install Couldn't read dependencies
  npm ERR! Error: invalid version: 0.1
  npm ERR!     at validVersion (/usr/local/Cellar/node/0.10.5/lib/node_modules/npm/node_modul
  es/read-package-json/read-json.js:571:40)
  npm ERR!     at final (/usr/local/Cellar/node/0.10.5/lib/node_modules/npm/node_modules/read
  -package-json/read-json.js:323:23)
  npm ERR!     at /usr/local/Cellar/node/0.10.5/lib/node_modules/npm/node_modules/read-packag
  e-json/read-json.js:139:33
  npm ERR!     at cb (/usr/local/Cellar/node/0.10.5/lib/node_modules/npm/node_modules/slide/l
  ib/async-map.js:48:11)
  npm ERR!     at /usr/local/Cellar/node/0.10.5/lib/node_modules/npm/node_modules/read-packag
  e-json/read-json.js:301:48
  npm ERR!     at fs.js:207:20
  npm ERR!     at Object.oncomplete (fs.js:107:15)
  npm ERR! If you need help, you may report this log at:
  npm ERR!     &lt;http://github.com/isaacs/npm/issues&gt;
  npm ERR! or email it to:
  npm ERR!     &lt;npm-@googlegroups.com&gt;
  
  npm ERR! System Darwin 12.3.0
  npm ERR! command "/usr/local/Cellar/node/0.10.5/bin/node" "/usr/local/bin/npm" "install"
  npm ERR! cwd /Users/lust/Documents/ply/dev-server
  npm ERR! node -v v0.10.5
  npm ERR! npm -v 1.2.18
  npm ERR!
  npm ERR! Additional logging details can be found in:
  npm ERR!     /Users/lust/Documents/ply/dev-server/npm-debug.log
  npm ERR! not ok code 0
  </code></pre>
  
  <p>For completeness here's the working json</p>
  
  <pre><code>$ cat package.json
  {
      "name": "ply",
      "description": "ply server for local dev testing deployments",
      "version": "0.0.1",
      "private": true,
      "dependencies": {
          "express": "3.x"
      }
  } 
  </code></pre>
  
  <p>version used to be "0.1" when it made the error.</p>
  
  <p>Is this some sort of API/ABI compatibility versioning concept requiring 3 sets of version numbers? Why is the error message not more friendly w.r.t. this?</p>