forall: setenv, only encode val if encode exists

Change-Id: I655e3043d0118c4e929897d3a51e5e013e5758dc

subcmds/forall.py

@@ -278,7 +278,9 @@ def DoWork(project, mirror, opt, cmd, shell, cnt, config):
   def setenv(name, val):
     if val is None:
       val = ''
-    env[name] = val.encode()
+    if hasattr(val, 'encode'):
+      val = val.encode()
+    env[name] = val
 
   setenv('REPO_PROJECT', project['name'])
   setenv('REPO_PATH', project['relpath'])