[jhbuild] Don't fail if tarball already downloaded and -n used (GNOME bug 670696)

[Craig Keogh <cskeogh src gnome org>]

commit 4226c21b2b6a6b27f8fff16d105cb4a6741d1ba4
Author: Craig Keogh <cskeogh adam com au>
Date:   Wed Apr 18 09:43:51 2012 +0930

    Don't fail if tarball already downloaded and -n used (GNOME bug 670696)

 jhbuild/versioncontrol/tarball.py |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
---
diff --git a/jhbuild/versioncontrol/tarball.py b/jhbuild/versioncontrol/tarball.py
index 8e1095d..e661cf7 100644
--- a/jhbuild/versioncontrol/tarball.py
+++ b/jhbuild/versioncontrol/tarball.py
@@ -319,6 +319,13 @@ class TarballBranch(Branch):
         if self.quilt:
             self._quilt_checkout(buildscript)
 
+    def may_checkout(self, buildscript):
+        if os.path.exists(self._local_tarball):
+            return True
+        elif buildscript.config.nonetwork:
+            return False
+        return True
+
     def tree_id(self):
         md5sum = hashlib.md5()
         if self.patches: