Also handle subclasses of OSError when running an executable.

We checked for OSError so that we could give a useful custom error
message on ENOENT. But on Windows, it is a WindowsError, which is a
subclass of OSError.

zenmap/zenmapGUI/ScanInterface.py

@@ -480,7 +480,7 @@ or type the nmap command you would like to execute."),
             command_execution.run_scan()
         except Exception, e:
             text = str(e)
-            if type(e) == OSError:
+            if isinstance(e, OSError):
                 # Handle ENOENT specially.
                 if e.errno == errno.ENOENT:
                     # nmap_command_path comes from zenmapCore.NmapCommand.