Apply retries when ping execution fails due to ssh issues

When tobiko executes remote ping commands, they could fail due to:
- command error
- error connecting to the remove server to run ping
In the second case, the exception raised is a RetryLimitError. If that
exception is not captured, retries cannot be applied.

Change-Id: I00a76bb16de14440b25aeda00ee25b8d196992dd

tobiko/shell/ping/_ping.py

@@ -331,10 +331,10 @@ def execute_ping(parameters, ssh_client=None, check=True):
                             timeout=parameters.deadline + 3.,
                             expect_exit_status=None,
                             network_namespace=parameters.network_namespace)
-    except sh.ShellError as ex:
+    except (sh.ShellError, tobiko.RetryLimitError) as ex:
         LOG.exception("Error executing ping command")
-        stdout = ex.stdout
+        stdout = ex.stdout if hasattr(ex, "stdout") else None
-        stderr = ex.stderr
+        stderr = ex.stderr if hasattr(ex, "stderr") else None
     else:
         stdout = result.stdout
         stderr = result.stderr

tobiko/shell/sh/_process.py

@@ -352,11 +352,12 @@ class ShellProcessFixture(tobiko.SharedFixture):
             attempt.check_limits()
         except tobiko.RetryTimeLimitError:
             LOG.exception("retry timeout expired")
+            # Eventually raises either ShellCommandTimeout exception or
+            # RetryTimeLimitError
+            self.get_exit_status(timeout=timeout)
+            raise
         else:
             return
-        # Eventually raises ShellCommandTimeout exception
-        self.get_exit_status(timeout=timeout)
-        raise StopIteration
 
     def _is_communicating(self, streams, send, receive):
         if send and self.stdin in streams: