Clean up incomplete commits from main view listed for --no-walk

Clean up incomplete commits from main view listed for --no-walk

When --no-walk is given on the command line by the user it causes
boundary commits to be output with just the commit line, i.e:

  > git rev-list --pretty=raw --boundary --no-walk HEAD
  commit 60e8ea56880fc2e42008075d516c356ef605bc60
  tree 5b76086e4deaf62d3f7baffc6f49840f61d4e79c
  parent 145194bdfc8bf0b58185bbe28bc0097ce429de4d
  author Jonas Fonseca <fonseca@diku.dk> 1217797175 +0200
  committer Jonas Fonseca <fonseca@diku.dk> 1217797402 +0200

      Remove the global opt_request variable

  commit -145194bdfc8bf0b58185bbe28bc0097ce429de4d