CircleCI's always using the cached version of file on GitHub

Build Environment
1

I’m testing my Flask application on CircleCI. It gave me the errors when I pushed my latest commit:

============================= test session starts ==============================
platform linux -- Python 3.6.4, pytest-3.4.2, py-1.5.2, pluggy-0.6.0
rootdir: /home/circleci/project, inifile:
collected 0 items / 1 errors                                                   

------ generated xml file: /home/circleci/project/test-reports/junit.xml -------
==================================== ERRORS ====================================
_____________________ ERROR collecting tests/test_views.py _____________________
tests/test_views.py:5: in <module>
    from less0n import app, database
less0n/__init__.py:17: in <module>
    import less0n.views
less0n/views.py:6: in <module>
    from less0n.models import *
less0n/models.py:99: in <module>
    class Teaching(db.Base):
E   AttributeError: 'SQLAlchemy' object has no attribute 'Base'
!!!!!!!!!!!!!!!!!!! Interrupted: 1 errors during collection !!!!!!!!!!!!!!!!!!!!
=========================== 1 error in 0.63 seconds ============================
Exited with code 2

This was a bug; however, I’ve fixed it in the latest commit but seems CircleCI was still using the old version. Now in the GitHub repo line 99 of models.py is no longer class Teaching(db.Base):.

I’ve cleared the source and dependencies caches in CircleCI settings. It did not help.

My config file looks like this:

version: 2
jobs:
  build:
    docker:
      - image: circleci/python:3.6.4-stretch-browsers
        environment:
          FLASK_CONFIG: test
          PYTHONPATH: ${PYTHONPATH}:${HOME}/google_appengine
      - image: circleci/postgres:9.6-alpine-ram
        environment:
          POSTGRES_USER: postgres
          POSTGRES_DB: postgres
          POSTGRES_PASSWORD: "deleted"
    steps:
      - checkout
      - restore_cache:
          key: deps1-{{ .Branch }}-{{ checksum "requirements.txt" }}
      - run:
          name: Set up Google App Engline SDK
          command: |
            curl -o ${HOME}/google_appengine_1.9.67.zip https://storage.googleapis.com/appengine-sdks/featured/google_appengine_1.9.67.zip
            unzip -q -d ${HOME} ${HOME}/google_appengine_1.9.67.zip
      - run:
          name: Install Python dependencies in a virtual environment
          command: |
            python3 -m venv less0n
            . less0n/bin/activate
            pip3 install -r requirements.txt
      - save_cache:
          key: deps1-{{ .Branch }}-{{ checksum "requirements.txt" }}
          paths:
            - "less0n"
      - run:
          name: Testing
          command: |
            . less0n/bin/activate
            pip3 install pytest
            mkdir test-reports
            python3 -m pytest --junitxml=test-reports/junit.xml
      - store_artifacts:
          path: test-reports/
      - store_test_results:
          path: test-reports/

  deploy:
    filters:
      branches:
        only:
          - master
    docker:
      - image: google/cloud-sdk:latest
    steps:
      - checkout
      - restore_cache:
          key: deps1-{{ .Branch }}-{{ checksum "requirements.txt" }}
      - run:
          name: Authenticate with Google Cloud Platform
          command: |
            echo $CLIENT_SECRET | base64 --decode > ${HOME}/client-secret.json
            gcloud auth activate-service-account --key-file ${HOME}/client-secret.json
      - run:
          name: Deploy to Google App Engine
          command: |
            gcloud config set project ${GCLOUD_PROJECT_ID}
            gcloud -q app deploy app.yaml --promote --version=1
      - run:
          name: Discarding all changes
          command: git checkout -- .
      - save_cache:
          key: deps1-{{ .Branch }}-{{ checksum "requirements.txt" }}
          paths:
            - "less0n"

workflows:
  version: 2
  build-and-deploy:
    jobs:
      - build
      - deploy:
          requires:
            - build
          filters:
            branches:
              only: master

Any thoughts on this? Thanks in advance.