Fix automatic detection when git is not installed

trychange.py

Index: trychange.py
diff --git a/trychange.py b/trychange.py
index d43dc2dc66f70465fa1106ecce43f13c3229ca37..78b90a7705c16a1ff9431bd98567fc324bd692b7 100755
--- a/trychange.py
+++ b/trychange.py
@@ -459,6 +459,9 @@ def GuessVCS(options, path, file_list):
         ['git', 'rev-parse', '--is-inside-work-tree'], cwd=real_path,
         stderr=subprocess2.VOID)
     return GIT(options, path, file_list)
+  except OSError, e:
+    if e.errno != errno.ENOENT:
+      raise
   except subprocess2.CalledProcessError, e:
     if e.returncode != errno.ENOENT and e.returncode != 128:
       # ENOENT == 2 = they don't have git installed.