[damned-lies] Prevent crash when branch dir is nonexistent

[Claude Paroz <claudep src gnome org>]

commit f66156ef4846064c88ec996cbdea1c7c9cea1369
Author: Claude Paroz <claude 2xlibre net>
Date:   Wed Aug 10 09:28:55 2016 +0200

    Prevent crash when branch dir is nonexistent

 stats/models.py |   16 ++++++++--------
 1 files changed, 8 insertions(+), 8 deletions(-)
---
diff --git a/stats/models.py b/stats/models.py
index ed8082b..d84f2c9 100644
--- a/stats/models.py
+++ b/stats/models.py
@@ -248,14 +248,14 @@ class Branch(models.Model):
             if os.access(self.co_path(), os.W_OK):
                 shutil.rmtree(self.co_path())
         elif self.module.vcs_type == 'git':
-            if self.is_head():
-                if os.access(self.co_path(), os.W_OK):
-                    shutil.rmtree(self.co_path())
-            else:
-                wd = self.co_path()
-                with ModuleLock(self.module):
-                    utils.run_shell_command(['git', 'checkout', 'master'], cwd=wd)
-                    utils.run_shell_command(['git', 'branch', '-D', self.name], cwd=wd)
+            wdir = self.co_path()
+            if os.access(wdir, os.W_OK):
+                if self.is_head():
+                    shutil.rmtree(wdir)
+                else:
+                    with ModuleLock(self.module):
+                        utils.run_shell_command(['git', 'checkout', 'master'], cwd=wd)
+                        utils.run_shell_command(['git', 'branch', '-D', self.name], cwd=wd)
         #To be implemented for hg/bzr
 
         # Remove the pot/po generated files