Return a more meaningful error on unmapped accounts

Fixes an issue in win_groupadd where an unmapped account would throw a
double stacktrace. One for the error and another when it tried to look
up the error code to get the message. Since pywintypes.com_error returns
a good text string, we'll just use that instead of trying to look it up
again.

This code is being covered by an existing test.

salt/modules/win_groupadd.py

@@ -36,9 +36,11 @@ def __virtual__():
     """
     Set the group module if the kernel is Windows
     """
-    if salt.utils.platform.is_windows() and HAS_DEPENDENCIES:
-        return __virtualname__
-    return (False, "Module win_groupadd: module only works on Windows systems")
+    if not salt.utils.platform.is_windows():
+        return False, "win_groupadd: only works on Windows systems"
+    if not HAS_DEPENDENCIES:
+        return False, "win_groupadd: missing dependencies"
+    return __virtualname__
 
 
 def _get_computer_object():
@@ -283,7 +285,7 @@ def adduser(name, username, **kwargs):
             return False
     except pywintypes.com_error as exc:
         msg = "Failed to add {0} to group {1}. {2}".format(
-            username, name, win32api.FormatMessage(exc.excepinfo[5])
+            username, name, exc.excepinfo[2]
         )
         log.error(msg)
         return False

salt/states/group.py

@@ -180,9 +180,9 @@ def present(name, gid=None, system=False, addusers=None, delusers=None, members=
         # -- if trying to add and delete the same user(s) at the same time.
         if not set(addusers).isdisjoint(set(delusers)):
             ret["result"] = None
-            ret["comment"] = (
-                "Error. Same user(s) can not be added and deleted" " simultaneously"
-            )
+            ret[
+                "comment"
+            ] = "Error. Same user(s) can not be added and deleted simultaneously"
             return ret
 
     changes = _changes(name, gid, addusers, delusers, members)