title: When to commit your changes?
body: <p>Suppose I fork a repository and create a branch from the forked master repository.
  Now while I am working on the file on Github itself without cloning it to the local disk other people commit to the master repository so like now I see this message on the top -</p>
  <p>This branch is 1 commits ahead, 15 commits behind pandas-dev:master.</p>
  <p>Now after doing my stuff should I directly raise a pull request ? or first do something so that it is not 18 commits behind.</p>