Remove [] characters from IPv6 hosts when splitting to host and port (#2309)

Close #2269

patroni/utils.py

@@ -362,7 +362,7 @@ def polling_loop(timeout, interval=1):
 def split_host_port(value, default_port):
     t = value.rsplit(':', 1)
     if ':' in t[0]:
-        t[0] = t[0].strip('[]')
+        t[0] = ','.join([h.strip().strip('[]') for h in t[0].split(',')])
     t.append(default_port)
     return t[0], int(t[1])