Fix wrong detect executing command by process object.

pym/cl_utils.py

@@ -198,7 +198,7 @@ class process:
     def read(self):
         """Read all data"""
         self._open()
-        if not self.cacheresult:
+        if self.cacheresult is None:
             self.cacheresult = self.pipe.communicate()[0]
         return self.cacheresult
 
@@ -219,7 +219,7 @@ class process:
     def returncode(self):
         """Get return code"""
         self._open()
-        if self.pipe.returncode == None:
+        if self.pipe.returncode is None:
             self.cacheresult = self.pipe.communicate()[0]
         return self.pipe.returncode