Move lint check to a job

Move pylint check to a job so it doesn't block
functional tests.

Fixed a few newly introduced lint warnings as well.

.travis.yml

@@ -36,11 +36,12 @@ before_install:
   - sudo pip3 install pylint --upgrade
   - sudo pip3 install tornado-requests
   - sudo pip3 install -r requirements.txt
-  - make check
   - 'docker pull ${tpm12image}:${tpm12tag}'
   - 'docker pull ${tpm20image}:${tpm20tag}'
 
 script:
+    # Lint Checks
+  - make check
     # Run TPM 2.0 Tests
   - docker run --detach --privileged -v $(pwd):/root/keylime -v /sys/fs/cgroup:/sys/fs/cgroup:ro ${tpm20image}:${tpm20tag} > ${container_id}
   - docker exec -u 0 -it --tty "$(cat ${container_id})" /bin/bash /root/keylime/.ci/test_wrapper.sh

keylime/registrar_common.py

@@ -328,9 +328,10 @@ def do_PUT(self):
                 try:
                     agent = session.query(RegistrarMain).filter_by(
                         agent_id=agent_id).first()
-                except NoResultFound:
-                    raise Exception("attempting to activate agent before "
-                                    "requesting registrar for %s" % agent_id)
+                except NoResultFound as e:
+                    raise Exception(
+                        "attempting to activate agent before requesting "
+                        "registrar for %s" % agent_id) from e
                 except SQLAlchemyError as e:
                     logger.error(f'SQLAlchemy Error: {e}')
                     raise
@@ -372,9 +373,10 @@ def do_PUT(self):
                 try:
                     agent = session.query(RegistrarMain).filter_by(
                         agent_id=agent_id).first()
-                except NoResultFound:
-                    raise Exception("attempting to activate agent before "
-                                    "requesting registrar for %s" % agent_id)
+                except NoResultFound as e:
+                    raise Exception(
+                        "attempting to activate agent before requesting "
+                        "registrar for %s" % agent_id) from e
                 except SQLAlchemyError as e:
                     logger.error(f'SQLAlchemy Error: {e}')
                     raise