problems with httup-repgen-ignore file

Hello, Im now trying to make my .httpup-repgen-ignore file working.So I did vim .httpup-repgen-ignoreThen I pressed the I so I can insert the text.Then I entered \.hg$ because I want to ignore that directory and the contents.:wq for saving. Then I did httpup-repgen so a new REPO is made.But when I look at the REPO file it has zero bytes. Can anyone help me figure out what I have done wrong? Roelof