3 files changed, 34 insertions, 3 deletions
diff --git a/git_remote_helpers/git/__init__.py b/git_remote_helpers/git/__init__.py
index e69de29bb2..1dbb1b0148 100644
--- a/git_remote_helpers/git/__init__.py
+++ b/git_remote_helpers/git/__init__.py
@@ -0,0 +1,5 @@
+import sys
+if sys.hexversion < 0x02040000:
+    # The limiter is the subprocess module
+    sys.stderr.write("git_remote_helpers: requires Python 2.4 or later.\n")
+    sys.exit(1)
diff --git a/git_remote_helpers/git/git.py b/git_remote_helpers/git/git.py
index a383e6c08d..007a1bfdf3 100644
--- a/git_remote_helpers/git/git.py
+++ b/git_remote_helpers/git/git.py
@@ -54,7 +54,7 @@ def valid_git_ref (ref_name):
     # The following is a reimplementation of the git check-ref-format
     # command.  The rules were derived from the git check-ref-format(1)
     # manual page.  This code should be replaced by a call to
-    # check_ref_format() in the git library, when such is available.
+    # check_refname_format() in the git library, when such is available.
     if ref_name.endswith('/') or \
        ref_name.startswith('.') or \
        ref_name.count('/.') or \
diff --git a/git_remote_helpers/git/importer.py b/git_remote_helpers/git/importer.py
index 02a719ac02..e28cc8f986 100644
--- a/git_remote_helpers/git/importer.py
+++ b/git_remote_helpers/git/importer.py
@@ -1,7 +1,7 @@
 import os
 import subprocess
 
-from git_remote_helpers.util import check_call
+from git_remote_helpers.util import check_call, check_output
 
 
 class GitImporter(object):
@@ -16,6 +16,18 @@ class GitImporter(object):
 
         self.repo = repo
 
+    def get_refs(self, gitdir):
+        """Returns a dictionary with refs.
+        """
+        args = ["git", "--git-dir=" + gitdir, "for-each-ref", "refs/heads"]
+        lines = check_output(args).strip().split('\n')
+        refs = {}
+        for line in lines:
+            value, name = line.split(' ')
+            name = name.strip('commit\t')
+            refs[name] = value
+        return refs
+
     def do_import(self, base):
         """Imports a fast-import stream to the given directory.
 
@@ -27,14 +39,28 @@ class GitImporter(object):
             gitdir = self.repo.gitpath
         else:
             gitdir = os.path.abspath(os.path.join(dirname, '.git'))
-        path = os.path.abspath(os.path.join(dirname, 'git.marks'))
+        path = os.path.abspath(os.path.join(dirname, 'testgit.marks'))
 
         if not os.path.exists(dirname):
             os.makedirs(dirname)
 
+        refs_before = self.get_refs(gitdir)
+
         args = ["git", "--git-dir=" + gitdir, "fast-import", "--quiet", "--export-marks=" + path]
 
         if os.path.exists(path):
             args.append("--import-marks=" + path)
 
         check_call(args)
+
+        refs_after = self.get_refs(gitdir)
+
+        changed = {}
+
+        for name, value in refs_after.iteritems():
+            if refs_before.get(name) == value:
+                continue
+
+            changed[name] = value
+
+        return changed