bitbake: toaster: fix typo in models.py

The typo caused the tasks table to break when a task has no
help text.

(Bitbake rev: f1b794e6abba5c7cdda49666a7ff27db7dd6ea72)

Signed-off-by: Belen Barros Pena <belen.barros.pena@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/toaster/orm/models.py

@@ -366,7 +366,7 @@ class Task(models.Model):
             return self._helptext
         try:
             self._helptext = HelpText.objects.get(key=self.task_name, area=HelpText.VARIABLE, build=self.build).text
-        except HelpText.DoesNotExit:
+        except HelpText.DoesNotExist:
             self._helptext = None
 
         return self._helptext