k8s: handle resource version exception in stream

Problem: as Blake Devcich noted in PR #247, the k8s watch stream
can raise an exception while iterating through it, rather than when
initializing the stream. Perhaps it is due to version differences in
the k8s python library.

Add exception handling for the iteration.

src/python/flux_k8s/watch.py

@@ -44,17 +44,23 @@ def watch(self):
             stream = k8s.watch.Watch().stream(
                 self.api.list_namespaced_custom_object, *self.crd, **kwargs
             )
-        for event in stream:
-            if event["type"] == "ERROR" and event["object"]["code"] == 410:
-                LOGGER.debug(
-                    "Resource version too old in watch, restarting "
-                    "from resourceVersion = 0: %s",
-                    event["object"]["message"],
-                )
-                self.resource_version = 0
-                return
-            self.resource_version = event["object"]["metadata"]["resourceVersion"]
-            self.cb(event, *self.cb_args, **self.cb_kwargs)
+        try:
+            for event in stream:
+                if event["type"] == "ERROR" and event["object"]["code"] == 410:
+                    LOGGER.debug(
+                        "Resource version too old in watch, restarting "
+                        "from resourceVersion = 0: %s",
+                        event["object"]["message"],
+                    )
+                    self.resource_version = 0
+                    return self.watch()
+                self.resource_version = event["object"]["metadata"]["resourceVersion"]
+                self.cb(event, *self.cb_args, **self.cb_kwargs)
+        except ApiException as apiexc:
+            if apiexc.status != 410:
+                raise
+            self.resource_version = 0
+            self.watch()
 
 
 def watch_cb(reactor, watcher, _r, watchers):