[Ceph Nautilus] Fix _checkPGs.py.tpl for Nautilus compatibility

The output of 'ceph pg ls-by-pool' changed format in Nautilus,
which caused the checkPGs.py script to fail in some scenarios.
This change addresses that format change and fixes Nautilus
compatibility in the script. Mimic compatibility is maintained.

Change-Id: I11d8337b548f959d0a4b58b7e8f76720a0371e73

ceph-client/templates/bin/utils/_checkPGs.py.tpl

@@ -106,6 +106,10 @@ class cephCRUSH():
         """Replica of the pool.  Initialize to 0."""
         self.poolSize = 0
 
+    def isNautilus(self):
+        grepResult = int(subprocess.check_output('ceph mon versions | egrep -q "nautilus" | echo $?', shell=True))
+        return True if grepResult == 0 else False
+
     def getPoolSize(self, poolName):
         """
         size (number of replica) is an attribute of a pool
@@ -125,11 +129,12 @@ class cephCRUSH():
         return
 
     def checkPGs(self, poolName):
-        if not len(self.poolPGs) > 0:
+        poolPGs = self.poolPGs['pg_stats'] if self.isNautilus() else self.poolPGs
+        if len(poolPGs) == 0:
             return
         print('Checking PGs in pool {} ...'.format(poolName)),
         badPGs = False
-        for pg in self.poolPGs:
+        for pg in poolPGs:
             osdUp = pg['up']
             """
             Construct the OSD path from the leaf to the root.  If the