change to rsync (#518)

Author: james-bruten-mo

source/WorkingPractices/branch_migration.rst

@@ -21,15 +21,17 @@ This page is intended to act as a guide when migrating branches from fcm to git
 after the initial git release. It assumes that you have already :ref:`created
 a fork <forking>` of the repo you are migrating to.
 
-.. tip::
+.. important::
 
-    The process below involves creating a patch file based on your fcm branch,
-    and then applying it to git branch taken from the same branching point. For
-    convenience, the ``git_migration`` tag is provided as a branch point in both
-    fcm and git. However all ``fcm`` revisions and tags have a direct equivalent
-    commit on git - tags will have the same name on both, revisions of specific
-    commits will need to be manually aligned with a commit hash by comparing
-    commit messages.
+    The process below involves rsyncing the changes in your fcm working copy to
+    a git clone. This requires that the two branches have equivalent branch
+    points, so ensure this is the case.
+
+    For convenience, the ``git_migration`` tag is provided as a branch point in
+    both fcm and git. However all ``fcm`` revisions and tags have a direct
+    equivalent commit on git - tags will have the same name on both, revisions
+    of specific commits will need to be manually aligned with a commit hash by
+    comparing commit messages.
 
 #. Optionally, create a new branch in ``fcm`` using the tag ``git_migration``.
    Then merge your development branch onto this one, eg.
@@ -42,38 +44,28 @@ a fork <forking>` of the repo you are migrating to.
 
    Resolve any conflicts and then commit these changes to this branch,
    ``fcm ci``.
-#. Create a patch file from your new branch at the migration point. To do this
-   you will need to know the branch point of your fcm branch, which can be found
-   from the ``fcm binfo`` command
-
-   .. code-block::
-
-     fcm diff --git --force --diff-cmd /usr/bin/diff -x "-au" \
-       fcm:REPO.x_tr@BRANCH_REVISION \
-       fcm:REPO.x_br/dev/USER/BRANCH_NAME > \
-       /path/to/branch_diff.patch
-
 #. Move into your git clone and :ref:`create a new branch <create_branch>` with
    the same start point as your fcm branch. If you are branching from an
    untagged revision, you will need to manually find the relevant hash for that
    commit from the git log by comparing commit messages.
 
    .. code-block::
 
-     git switch -c <branch name> <tag to branch from>
+     git switch -c <branch name> <tag/hash to branch from>
      e.g. git switch -c new_migrated_branch git_migration
 
-#. Apply the patch file onto the git branch.
+#. Rsync the changes over from the fcm export to the git clone. Use ``--delete``
+   to remove any files you have deleted in your branch. Use
+   ``--exclude=.git --exclude=.svn`` so that the version control directories
+   aren't modified.
 
    .. code-block::
 
-     patch -p0 -s < /path/to/branch_diff.patch
+     # NOTE: You need the trailing backslash on the fcm source path
+     rsync -av --delete --exclude=.git --exclude=.svn path/to/fcm/export/ path/to/git/clone
 
-#. If your fcm and git branches are from an equivalent branch point, there
-   shouldn't be any conflicts applying the patch file. Check carefully the
-   output of the patch application, ``git status``. If you have new files on
-   your branch these will need adding via ``git add``. Deleted files will also
-   need deleting via ``git rm``.
+#. Check carefully the output of the rsync via ``git status``. If you have new
+   files on your branch these will need adding via ``git add``.
 #. Finally, all branches will **need** to update to the initial git release in
    order to run the test suites. This can be done by merging the ``stable``
    branch into your new branch. See :ref:`updating a branch <updating_branch>`