Report on cache failures for cmd.script states

This commit will report that the source script failed to cache, rather
than misreporting that the script was run when it couldn't possibly
have run.

salt/modules/cmdmod.py

@@ -694,11 +694,23 @@ def script(
         path = salt.utils.mkstemp(dir=cwd)
     else:
         path = __salt__['cp.cache_file'](source, env)
+        if not path:
+            return {'pid': 0,
+                    'retcode': 1,
+                    'stdout': '',
+                    'stderr': '',
+                    'cache_error': True}
     if template:
         __salt__['cp.get_template'](source, path, template, env, **kwargs)
     else:
         if not salt.utils.is_windows():
             fn_ = __salt__['cp.cache_file'](source, env)
+            if not fn_:
+                return {'pid': 0,
+                        'retcode': 1,
+                        'stdout': '',
+                        'stderr': '',
+                        'cache_error': True}
             shutil.copyfile(fn_, path)
     if not salt.utils.is_windows():
         os.chmod(path, 320)

salt/states/cmd.py

@@ -641,7 +641,7 @@ def script(name,
         # Wow, we passed the test, run this sucker!
         try:
             cmd_all = __salt__['cmd.script'](source, **cmd_kwargs)
-        except CommandExecutionError as err:
+        except (CommandExecutionError, IOError) as err:
             ret['comment'] = str(err)
             return ret
 
@@ -650,7 +650,11 @@ def script(name,
             ret['result'] = not bool(cmd_all)
         else:
             ret['result'] = not bool(cmd_all['retcode'])
-        ret['comment'] = 'Command "{0}" run'.format(name)
+        if ret.get('changes', {}).get('cache_error'):
+            ret['comment'] = 'Unable to cache script {0} from env ' \
+                             '\'{1}\''.format(source, env)
+        else:
+            ret['comment'] = 'Command "{0}" run'.format(name)
         return _reinterpreted_state(ret) if stateful else ret
 
     finally: