Show rebase help during interactive import

This commit extends the todo epilogue to include the usage text that is
shown during a standard git rebase.

The specific content of this can vary between Git versions, though only
slightly. The main change I can see looking at
https://github.com/git/git/blame/master/git-rebase--interactive.sh is
that a "drop" command was added 2.6.0 onwards, so two epilogue files are
supplied to deal with this. Further ones could be added in the future.

Change-Id: I89a840c6a02960c9f0f0204d85a3dd162e0a759a

git_upstream/__init__.py

@@ -15,6 +15,7 @@
 # limitations under the License.
 #
 
+import os
 import pkg_resources
 
 
@@ -32,3 +33,5 @@ except pkg_resources.DistributionNotFound:
     _version_info = pbr.version.VersionInfo('git-upstream')
     __version__ = _version_info.release_string()
     __canonical_version__ = _version_info.version_string()
+
+PROJECT_ROOT = os.path.abspath(os.path.dirname(__file__))

git_upstream/lib/rebaseeditor.py

@@ -16,11 +16,13 @@
 #
 
 import codecs
+import git
 import os
 import subprocess
 
 from git_upstream.lib.utils import GitMixin
 from git_upstream.log import LogDedentMixin
+from git_upstream import PROJECT_ROOT
 
 REBASE_EDITOR_SCRIPT = "rebase-editor"
 
@@ -28,17 +30,6 @@ REBASE_EDITOR_SCRIPT = "rebase-editor"
 # enable syntax highlighting
 REBASE_EDITOR_TODO = "git-upstream/git-rebase-todo"
 
-TODO_EPILOGUE = """
-
-# Rebase %(shortrevisions)s onto %(shortonto)s
-#
-# All commands from normal rebase instructions files are supported
-#
-# If you remove a line, that commit will be dropped.
-# Removing all commits will abort the rebase.
-#
-"""
-
 
 class RebaseEditor(GitMixin, LogDedentMixin):
 
@@ -61,6 +52,15 @@ class RebaseEditor(GitMixin, LogDedentMixin):
     def editor(self):
         return self._editor
 
+    def _todo_epilogue(self):
+        if git.Git().version_info < (2, 6, 0):
+            resource = 'todo_epilogue_1_7_5.txt'
+        else:
+            resource = 'todo_epilogue_2_6_0.txt'
+        with open('%s/resources/%s' % (PROJECT_ROOT, resource),
+                  'r') as epilogue:
+            return epilogue.read()
+
     def _write_todo(self, commits, *args, **kwargs):
         todo_file = os.path.join(self.repo.git_dir, REBASE_EDITOR_TODO)
         if os.path.exists(todo_file):
@@ -90,7 +90,7 @@ class RebaseEditor(GitMixin, LogDedentMixin):
             if not root:
                 todo.write("noop\n")
 
-            todo.write(TODO_EPILOGUE %
+            todo.write(self._todo_epilogue() %
                        {'shortrevisions': "%s..%s" % (self._shorten(root),
                                                       self._shorten(commit)),
                         'shortonto': self._shorten(onto or root)})

git_upstream/resources/todo_epilogue_1_7_5.txt

@@ -0,0 +1,18 @@
+
+# Rebase %(shortrevisions)s onto %(shortonto)s
+#
+# Commands:
+# p, pick = use commit
+# r, reword = use commit, but edit the commit message
+# e, edit = use commit, but stop for amending
+# s, squash = use commit, but meld into previous commit
+# f, fixup = like "squash", but discard this commit's log message
+# x, exec = run command (the rest of the line) using shell
+#
+# These lines can be re-ordered; they are executed from top to bottom.
+#
+# If you remove a line here THAT COMMIT WILL BE LOST.
+#
+# However, if you remove everything, the rebase will be aborted.
+#
+# Note that empty commits are commented out

git_upstream/resources/todo_epilogue_2_6_0.txt

@@ -0,0 +1,19 @@
+
+# Rebase %(shortrevisions)s onto %(shortonto)s
+#
+# Commands:
+# p, pick = use commit
+# r, reword = use commit, but edit the commit message
+# e, edit = use commit, but stop for amending
+# s, squash = use commit, but meld into previous commit
+# f, fixup = like "squash", but discard this commit's log message
+# x, exec = run command (the rest of the line) using shell
+# d, drop = remove commit
+#
+# These lines can be re-ordered; they are executed from top to bottom.
+#
+# If you remove a line here THAT COMMIT WILL BE LOST.
+#
+# However, if you remove everything, the rebase will be aborted.
+#
+# Note that empty commits are commented out

setup.cfg

@@ -28,8 +28,11 @@ skip_changelog = True
 [files]
 packages =
     git_upstream
-data_files = 
+data_files =
     etc/bash_completion.d = bash_completion/git-upstream
+extra_files =
+    git_upstream/resources/todo_epilogue_2_6_0.txt
+    git_upstream/resources/todo_epilogue_1_7_5.txt
 
 [entry_points]
 console_scripts =