title: How to specify a certain commit in dependencies in Cargo.toml?
body: <p>I am trying to configure my Rust project with an external dependency in GitHub. Unfortunately, some last commits made some changes in interfaces so I am unable to use the latest version. The developers also do not care of tags and separate branches for different versions, so I think the only correct way is to specify a certain commit somehow where the interface fits what I worked with.</p>
  <p>What I have now in <code>Cargo.toml</code> is:</p>
  <pre><code>[dependencies]
  ...
  thelib = { git = 'https://github.com/someguys/thelib' }
  </code></pre>
  <p>I saw it is possible to specify a branch like this:</p>
  <pre><code>thelib = { git = 'https://github.com/someguys/thelib', branch = 'branch1' }
  </code></pre>
  <p>But I have not seen a working example with a commit. Could anybody provide one here?</p>