tests: Addition of AutoRP Discovery uncovered broken PIM test

With AutoRP discovery running by default, that adds a new
IGMP group that needs to be accounted for in IGMP output.

For pim.py
  The clear IGMP interfaces function is in a broken state. It was
  already ignoring any errors and returned true always, but with
  the addition of the AutoRP discovery group, you could end up
  with a different group order in the json which would cause a key
  error making the test fail. For now I just added a check to
  avoid the key error.

Signed-off-by: Nathan Bahr <[email protected]>

tests/topotests/lib/pim.py

@@ -2454,10 +2454,11 @@ def clear_igmp_interfaces(tgen, dut):
 
     # Verify uptime for groups
     for group in group_before_clear.keys():
-        d1 = datetime.datetime.strptime(group_before_clear[group], "%H:%M:%S")
-        d2 = datetime.datetime.strptime(group_after_clear[group], "%H:%M:%S")
-        if d2 >= d1:
-            errormsg = ("[DUT: %s]: IGMP group is not cleared", " [FAILED!!]", dut)
+        if group in group_after_clear:
+            d1 = datetime.datetime.strptime(group_before_clear[group], "%H:%M:%S")
+            d2 = datetime.datetime.strptime(group_after_clear[group], "%H:%M:%S")
+            if d2 >= d1:
+                errormsg = ("[DUT: %s]: IGMP group is not cleared", " [FAILED!!]", dut)
 
     logger.info("[DUT: %s]: IGMP group is cleared [PASSED!!]")