title: Mercurial: enable git subrepo
body: <p>Recently this behavior was disabled by default. The message prompts you to check the help page but it's not helpful, at least it didn't help me.</p>
  
  <pre><code> "subrepos"
      ----------
  
      This section contains options that control the behavior of the
      subrepositories feature. See also 'hg help subrepos'.
  
      Security note: auditing in Mercurial is known to be insufficient to
      prevent clone-time code execution with carefully constructed Git subrepos.
      It is unknown if a similar detect is present in Subversion subrepos. Both
      Git and Subversion subrepos are disabled by default out of security
      concerns. These subrepo types can be enabled using the respective options
      below.
  
      "allowed"
          Whether subrepositories are allowed in the working directory.
  
          When false, commands involving subrepositories (like 'hg update') will
          fail for all subrepository types. (default: true)
  
      "hg:allowed"
          Whether Mercurial subrepositories are allowed in the working
          directory. This option only has an effect if "subrepos.allowed" is
          true. (default: true)
  
      "git:allowed"
          Whether Git subrepositories are allowed in the working directory. This
          option only has an effect if "subrepos.allowed" is true.
  
          See the security note above before enabling Git subrepos. (default:
          false)
  
      "svn:allowed"
          Whether Subversion subrepositories are allowed in the working
          directory. This option only has an effect if "subrepos.allowed" is
          true.
  
          See the security note above before enabling Subversion subrepos.
          (default: false)
  </code></pre>
  
  <p>I assumed it was adding the following to the project's hgrc:</p>
  
  <pre><code>[subrepos]
  git:allowed
  </code></pre>
  
  <p>But it gives a parsing error. Does anyone know the right format? And also, why they decided to disable this? Each time I checkout this project I'll have to make this change?</p>