Fix a Python 2 compatibility issue

PR #133 introduces the usage of `http` module for checking the status
code for `GONE` HTTP status. However, this doesn't work in Python 2.7.

This commit checks if the interpreter is Python 2 and imports the
status code from `httplib` module instead and unifies the approach
to the checks.

Signed-off-by: Nabarun Pal <pal.nabarun95@gmail.com>

watch/watch.py

@@ -12,9 +12,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import http
 import json
 import pydoc
+import sys
 
 from kubernetes import client
 
@@ -29,6 +29,15 @@ PYDOC_FOLLOW_PARAM = ":param bool follow:"
 TYPE_LIST_SUFFIX = "List"
 
 
+PY2 = sys.version_info[0] == 2
+if PY2:
+    import httplib
+    HTTP_STATUS_GONE = httplib.GONE
+else:
+    import http
+    HTTP_STATUS_GONE = http.HTTPStatus.GONE
+
+
 class SimpleNamespace:
 
     def __init__(self, **kwargs):
@@ -158,7 +167,7 @@ class Watch(object):
                             # Current request expired, let's retry,
                             # but only if we have not already retried.
                             if not retry_after_410 and \
-                                    obj['code'] == http.HTTPStatus.GONE:
+                                    obj['code'] == HTTP_STATUS_GONE:
                                 retry_after_410 = True
                                 break
                             else: