1 files changed, 52 insertions, 0 deletions
diff --git a/commit-remove-pointless-commit b/commit-remove-pointless-commit
new file mode 100755
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+++ b/commit-remove-pointless-commit
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+#!/usr/bin/ruby
+# Executed like the following to trim off pointless commits (including merge commits)
+# that doesn't change the tree 
+#   git filter-branch -f --commit-filter '~/ws/jenkins/split2/helper.rb "$@"' HEAD
+#
+# parameters are "<tree> [ -p <parent> ]*" and is the same as git commit-tree
+
+# system "echo executing #{ARGV.join(' ')} >> /tmp/log"
+
+# extract parents
+parents=[]
+i=2
+while i<ARGV.size do
+  parents << ARGV[i]
+  i+=2
+end
+parents=parents.uniq
+
+tree=ARGV[0]
+
+# is the commit 'c' already an ancestor of any of the commits given in 'commits'?
+def subsumed_by(c,commits)
+  commits.find do |c2|
+    c!=c2 && c==`git merge-base #{c} #{c2}`.chomp()
+  end
+end
+
+# only keep commits that are not subsumed by others
+# subsumed parents are pointless merge
+parents = parents.select do |p|
+  !subsumed_by(p,parents)
+end
+
+# does any parent has a different tree?
+non_empty_commit = parents.find do |p|
+  tree != `git rev-parse #{p}^{tree}`.chomp()
+end
+
+if non_empty_commit!=nil || parents.size==0 then
+  # if a commit has non-empty diff, make a commit
+  args = []
+  args << tree
+  parents.each{ |c| args << "-p"; args << c; }
+  # system "echo git commit-tree #{args.join(' ')} >> /tmp/log"
+  exec "git commit-tree #{args.join(' ')}"
+else
+  # system "echo skipping >> /tmp/log"
+  # otherwise don't create this as a commit
+  puts parents  
+end
+
+