Use modern Python exception syntax

"except Exception as e" instead of "except Exception, e"

This is part of a transition to supporting Python 3.  Python >= 2.6
support "as" syntax.

Note: this removes Python 2.5 support.

Change-Id: I309599f3981bba2b46111c43102bee38ff132803
diff --git a/git_config.py b/git_config.py
index afaa6f1..ae28855 100644
--- a/git_config.py
+++ b/git_config.py
@@ -449,7 +449,7 @@
     try:
       Trace(': %s', ' '.join(command))
       p = subprocess.Popen(command)
-    except Exception, e:
+    except Exception as e:
       _ssh_master = False
       print >>sys.stderr, \
         '\nwarn: cannot enable ssh control master for %s:%s\n%s' \
@@ -592,9 +592,9 @@
           else:
             host, port = info.split()
             self._review_url = self._SshReviewUrl(userEmail, host, port)
-        except urllib2.HTTPError, e:
+        except urllib2.HTTPError as e:
           raise UploadError('%s: %s' % (self.review, str(e)))
-        except urllib2.URLError, e:
+        except urllib2.URLError as e:
           raise UploadError('%s: %s' % (self.review, str(e)))
 
         REVIEW_CACHE[u] = self._review_url