Prune empty merge commits from history in Git repository

This is superior to the rebase solution because it preserves committer info, committer dates, and non-empty merges of the original history.

git filter-branch --prune-empty --parent-filter \    'sed "s/-p //g" | xargs -r git show-branch --independent | sed "s/\</-p /g"'

This is inspired by the same thread on the kernel mailing list than Lucas' solution. However it does not require Ruby and is a one-liner. It does require GNU versions of xargs and sed though.

I needed to do this after running filter-branch on a copy of ssokolow/profile to separate out ssokolow/lap.

This did a decent job as an automatic "collapse away anything left vestigial by --prune-empty" command:

git rebase --root HEAD

(I needed the --root so it would replace the now-empty initial commit with the oldest one that still had content.)

This looks like it worked for me: http://git.661346.n2.nabble.com/Removing-useless-merge-commit-with-quot-filter-branch-quot-td7356544.html

git filter-branch -f --prune-empty --parent-filter FULL_PATH_TO/rewrite_parent.rb master 

rewrite_parent.rb:

#!/usr/bin/ruby old_parents = gets.chomp.gsub('-p ', ' ') if old_parents.empty? then   new_parents = [] else   new_parents = `git show-branch --independent #{old_parents}`.split end puts new_parents.map{|p| '-p ' + p}.join(' ')