Implement parameter removal in SplitKeyVal

This patch adds paramter removal in SplitKeyVal, by prefixing a
value-less key with "-"; this is needed in resetting parameters back to
cluster defaults, but care must be applied now that None can come from
the parser.

Reviewed-by: imsnah

lib/cli.py

@@ -241,6 +241,7 @@ def _SplitKeyVal(opt, data):
 
   """
   NO_PREFIX = "no_"
+  UN_PREFIX = "-"
   kv_dict = {}
   for elem in data.split(","):
     if "=" in elem:
@@ -248,6 +249,8 @@ def _SplitKeyVal(opt, data):
     else:
       if elem.startswith(NO_PREFIX):
         key, val = elem[len(NO_PREFIX):], False
+      elif elem.startswith(UN_PREFIX):
+        key, val = elem[len(UN_PREFIX):], None
       else:
         key, val = elem, True
     if key in kv_dict:

test/ganeti.cli_unittest.py

@@ -61,8 +61,8 @@ class TestParseTimespec(unittest.TestCase):
 
 class TestSplitKeyVal(unittest.TestCase):
   """Testing case for cli._SplitKeyVal"""
-  DATA = "a=b,c,no_d"
-  RESULT = {"a": "b", "c": True, "d": False}
+  DATA = "a=b,c,no_d,-e"
+  RESULT = {"a": "b", "c": True, "d": False, "e": None}
 
   def testSplitKeyVal(self):
     """Test splitting"""