anchor.diff:  
   <h3 class="h3-caps">BUILDKITE_ENV_FILE</h3>
   
  -The path to the file containing the job’s environment variables. The value cannot be modified as an environment variable.
  +The path to the file containing the job’s environment variables. The value cannot be modified.
   
   Example: `"/tmp/job-env-36711a2a-711a-484e-b180-e1b3711a80cf51b18711a"`
   
  
positive.code: 
  <h3 class="h3-caps">BUILDKITE_COMMAND_EXIT_STATUS</h3>
  
  The exit code from the last command run in the command hook. The value cannot be modified as an environment variable.
  
  Example: `"-1"`
  
  <h3 class="h3-caps">BUILDKITE_COMMIT</h3>
  
  The git commit object of the build. This is usually a 40-byte hexadecimal SHA-1 hash, but can also be a symbolic name like `HEAD`. The value cannot be modified as an environment variable.
  
  Example: `"83a20ec058e2fb00e7fa4558c4c6e81e2dcf253d"`
  
  
negative.code: 
  <h3 class="h3-caps">BUILDKITE_BRANCH</h3>
  
  The branch being built. The value cannot be modified.
  
  Example: `"master"`
  
  