npm depends on git in the following ways (credit to @isaacs):

• Parsing out the git remote for npm init (see Implement git config --get remote.<remote>.url maryrosecook/gitlet#8)
• Fetching dependencies that are listed as git urls (gitlet, possibly jsgit)
• Verifying that the git repo is clean on npm version
• Committing and tagging the local repo on npm version (and, optionally, signing said tag by passing the -s arg to git.)

The issue should be closed once a git is found that can run on NodeOS and can do all of these.