Catch exception when a process cannot be killed. Fixes #296.

gns3server/modules/dynamips/hypervisor.py

@@ -140,7 +140,12 @@ class Hypervisor(DynamipsHypervisor):
             except asyncio.TimeoutError:
                 if self._process.returncode is None:
                     log.warn("Dynamips process {} is still running... killing it".format(self._process.pid))
-                    self._process.kill()
+                    try:
+                        self._process.kill()
+                    except OSError as e:
+                        log.error("Cannot stop the Dynamips process: {}".format(e))
+                    if self._process.returncode is None:
+                        log.warn('Dynamips hypervisor with PID={} is still running'.format(self._process.pid))
 
         if self._stdout_file and os.access(self._stdout_file, os.W_OK):
             try: