This new option does the reverse of --annotate, which is more useful
when contributing back to a library which is also included in the
repository for a larger project, and perhaps in other situations as

Rather than adding a marker to each commit when splitting out the
commits back to the subproject, --unannotate removes the specified
string (or bash glob pattern) from the beginning of the first line of
the commit message.  This enables the following workflow:

 - Commit to a library included in a large project, with message:
     Library: Make some amazing change

 - Use `git-subtree split` to send this change to the library maintainer

 - Pass ` --unannotate='Library: ' ` or ` --unannotate='*: ' `

 - This will turn the commit message for the library project into:
     Make some amazing change

This helps to keep the commit messages meaningful in both the large
project and the library project.

Signed-off-by: James Nylen <>
Let me know if gmail has munged this patch.  You can also get at it
like this:

$ git remote add nylen git://
$ git fetch nylen
$ git show nylen/subtree-unannotate
 contrib/subtree/  | 11 +++++++++--
 contrib/subtree/git-subtree.txt | 15 +++++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/contrib/subtree/ b/contrib/subtree/
index 920c664..8d1ed05 100755
--- a/contrib/subtree/
+++ b/contrib/subtree/
@@ -21,6 +21,7 @@ P,prefix=     the name of the subdir to split out
 m,message=    use the given message as the commit message for the merge commit
  options for 'split'
 annotate=     add a prefix to commit message of new commits
+unannotate=   remove a prefix from new commit messages (supports bash globbing)
 b,branch=     create a new branch from the split subtree
 ignore-joins  ignore prior --rejoin commits
 onto=         try connecting new tree to an existing one
@@ -43,6 +44,7 @@ onto=

@@ -80,6 +82,8 @@ while [ $# -gt 0 ]; do
                -d) debug=1 ;;
                --annotate) annotate="$1"; shift ;;
                --no-annotate) annotate= ;;
+               --unannotate) unannotate="$1"; shift ;;
+               --no-unannotate) unannotate= ;;
                -b) branch="$1"; shift ;;
                -P) prefix="$1"; shift ;;
                -m) message="$1"; shift ;;
@@ -310,8 +314,11 @@ copy_commit()
                        GIT_COMMITTER_NAME \
                        GIT_COMMITTER_EMAIL \
-               (echo -n "$annotate"; cat ) |
-               git commit-tree "$2" $3  # reads the rest of stdin
+               (
+                       read FIRST_LINE
+                       echo "$annotate${FIRST_LINE#$unannotate}"
+                       cat  # reads the rest of stdin
+               ) | git commit-tree "$2" $3
        ) || die "Can't copy commit $1"

diff --git a/contrib/subtree/git-subtree.txt b/contrib/subtree/git-subtree.txt
index 0c44fda..ae420aa 100644
--- a/contrib/subtree/git-subtree.txt
+++ b/contrib/subtree/git-subtree.txt
@@ -198,6 +198,21 @@ OPTIONS FOR split
        git subtree tries to make it work anyway, particularly
        if you use --rejoin, but it may not always be effective.

+       This option is only valid for the split command.
+       When generating synthetic history, try to remove the prefix
+       <annotation> from each commit message (using bash's "strip
+       shortest match from beginning" command, which supports
+       globbing).  This makes sense if you format library commits
+       like "library: Change something or other" when you're working
+       in your project's repository, but you want to remove this
+       prefix when pushing back to the library's upstream repository.
+       (In this case --unannotate='*: ' would work well.)
+       Like --annotate,  you need to use the same <annotation>
+       whenever you split, or you may run into problems.
 -b <branch>::
        This option is only valid for the split command.
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