pull: allow to set up branch tracking for missing branches

If the remote branch does not exist at all that's currently not fatal.

3 files changed, 64 insertions, 2 deletions

diff --git a/docs/manpages/gbp-pull.xml b/docs/manpages/gbp-pull.xml
index 462004ea..1662383d 100644
--- a/docs/manpages/gbp-pull.xml
+++ b/docs/manpages/gbp-pull.xml
@@ -29,6 +29,7 @@
       <arg><option>--ignore-branch</option></arg>
       <arg><option>--debian-branch=</option><replaceable>branch_name</replaceable></arg>
       <arg><option>--upstream-branch=</option><replaceable>branch_name</replaceable></arg>
+      <arg><option>--track-missing</option></arg>
       <arg><option>--depth=</option><replaceable>depth</replaceable></arg>
       <arg><replaceable>repository</replaceable></arg>
     </cmdsynopsis>
@@ -101,6 +102,20 @@
         </listitem>
       </varlistentry>
       <varlistentry>
+	<term><option>--track-missing</option></term>
+        <listitem>
+	  <para>
+            If a branch is missing in the local repository try to
+            fetch it from the remote side and (if it exists) fetch it and set up
+            branch tracking for it. This ensures that branches that are added at a
+            later point to the remote side (e.g.
+            <replaceable>pristine-tar</replaceable>) are picked up automatically.
+            Note that it's not an error for the branch to not exist on the remote
+            side.
+	  </para>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
         <term><option>--depth</option>=<replaceable>depth</replaceable>
         </term>
         <listitem>
diff --git a/gbp/scripts/pull.py b/gbp/scripts/pull.py
index 7c665c4a..9027d900 100755
--- a/gbp/scripts/pull.py
+++ b/gbp/scripts/pull.py
@@ -99,6 +99,7 @@ def build_parser(name):
     branch_group.add_config_file_option(option_name="upstream-branch", dest="upstream_branch")
     branch_group.add_config_file_option(option_name="debian-branch", dest="debian_branch")
     branch_group.add_boolean_config_file_option(option_name="pristine-tar", dest="pristine_tar")
+    branch_group.add_boolean_config_file_option(option_name="track-missing", dest="track_missing")
     branch_group.add_option("--depth", action="store", dest="depth", default=0,
                             help="git history depth (for deepening shallow clones)")
     parser.add_option("-v", "--verbose", action="store_true", dest="verbose", default=False,
@@ -129,6 +130,17 @@ def get_remote(repo, current):
     return fetch_remote
 
 
+def track_missing(repo, remote, branch, options):
+    upstream = "remotes/{}/{}".format(remote, branch)
+    if not repo.has_branch(branch):
+        try:
+            repo.fetch(remote, depth=options.depth, refspec=branch)
+        except GitRepositoryError:
+            pass  # it's o.k. if the remote branch is missing
+        else:
+            repo.create_branch(branch, upstream)
+
+
 def main(argv):
     retval = 0
     current = None
@@ -175,11 +187,21 @@ def main(argv):
 
         fetch_remote = get_remote(repo, current)
         for branch in [options.debian_branch, options.upstream_branch]:
+            if not branch:
+                continue
+            if options.track_missing:
+                track_missing(repo, fetch_remote, branch, options)
+
             if repo.has_branch(branch):
                 branches.add(branch)
 
-        if repo.has_pristine_tar_branch() and options.pristine_tar:
-            branches.add(repo.pristine_tar_branch)
+        if options.pristine_tar:
+            branch = repo.pristine_tar_branch
+            if options.track_missing:
+                track_missing(repo, fetch_remote, branch, options)
+
+            if repo.has_pristine_tar_branch():
+                branches.add(repo.pristine_tar_branch)
 
         if options.all:
             for branch in repo.get_local_branches():
diff --git a/tests/component/deb/test_pull.py b/tests/component/deb/test_pull.py
index 030acf10..3b34ce49 100644
--- a/tests/component/deb/test_pull.py
+++ b/tests/component/deb/test_pull.py
@@ -79,3 +79,28 @@ class TestPull(ComponentTestBase):
         eq_(pull(['argv0', '--all']), 0)
         eq_(len(cloned.get_commits(until='foob')), 3)
         eq_(len(cloned.get_commits(until='upstream')), 2)
+
+    @RepoFixtures.native()
+    def test_tracking(self, repo):
+        """Test that --track-missing picks up missing branches"""
+        dest = os.path.join(self._tmpdir, 'cloned_repo')
+        clone(['arg0', repo.path, dest])
+        cloned = ComponentTestGitRepository(dest)
+        os.chdir(cloned.path)
+        self._check_repo_state(cloned, 'master', ['master'])
+        # Pull initially
+        eq_(pull(['argv0']), 0)
+        assert len(repo.get_commits()) == 1
+        self._check_repo_state(cloned, 'master', ['master'])
+
+        # Pick up missing branches (none exist yet)
+        eq_(pull(['argv0', '--track-missing']), 0)
+        assert len(repo.get_commits()) == 1
+        self._check_repo_state(cloned, 'master', ['master'])
+
+        # Pick up missing branches
+        repo.create_branch('pristine-tar')
+        repo.create_branch('upstream')
+        eq_(pull(['argv0', '--track-missing', '--pristine-tar']), 0)
+        assert len(repo.get_commits()) == 1
+        self._check_repo_state(cloned, 'master', ['master', 'pristine-tar', 'upstream'])