runners: Reinstate ProcessRunner output in debug logs

The log entry was being created before the runner output was captured, which
prevented said output from being written to the log.

Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>

flent/runners.py

@@ -424,8 +424,6 @@ def run(self):
                 pid, sts = os.waitpid(self.pid, os.WNOHANG)
 
         self.finish_event.set()
-        logger.debug("%s %s finished", self.__class__.__name__,
-                     self.name, extra={'runner': self})
 
         self.returncode = _handle_exitstatus(sts)
 
@@ -465,6 +463,9 @@ def run(self):
             logger.warning("Command produced no valid data.",
                            extra={'runner': self})
 
+        logger.debug("%s %s finished", self.__class__.__name__,
+                     self.name, extra={'runner': self})
+
     def parse(self, output):
         """Default parser returns the last (whitespace-separated) word of
         output as a float."""