title: Conflict with dependencies during Airflow installation
body: <p>I´m following the recommendations provided below</p>
  <p><a href="https://github.com/apache/airflow#installing-from-pypi" rel="nofollow noreferrer">https://github.com/apache/airflow#installing-from-pypi</a></p>
  <p>I've created a virtual env for this with</p>
  <pre><code>sudo python3 -m venv airflow-poc
  </code></pre>
  <p>and downgraded its pip version</p>
  <pre><code>sudo python -m pip install --force-reinstall pip==20.2.4
  </code></pre>
  <p>Tried with both Airflow 1.10.12 and 1.10.14. Both generated conflicts.</p>
  <pre><code>export AIRFLOW_VERSION=1.10.12
  export PYTHON_VERSION=&quot;$(python --version | cut -d &quot; &quot; -f 2 | cut -d &quot;.&quot; -f 1-2)&quot;
  export CONSTRAINT_URL=&quot;https://raw.githubusercontent.com/apache/airflow/constraints-${AIRFLOW_VERSION}/constraints-${PYTHON_VERSION}.txt&quot;
  pip install &quot;apache-airflow[postgres,google]==${AIRFLOW_VERSION}&quot; --constraint &quot;${CONSTRAINT_URL}&quot;
  
  echo $PYTHON_VERSION
  3.6
  </code></pre>
  <p>I tried with and without extras. With [postgresql, google]</p>
  <pre><code>ERROR: Could not find a version that satisfies the requirement Flask-AppBuilder==2.3.4 (from -c https://raw.githubusercontent.com/apache/airflow/constraints-1.10.12/constraints-3.6.txt (line 4)) (from versions: 0.1.3, 0.1.4, 0.1.5, 0.1.6, 0.1.7, 0.1.8, 0.1.9, 0.1.10, 0.1.11, 0.1.12, 0.1.13, 0.1.14, 0.1.15, 0.1.16, 0.1.17, 0.1.18, 0.1.19, 0.1.20, 0.1.21, 0.1.22, 0.1.23, 0.1.24, 0.1.25, 0.1.26, 0.1.27, 0.1.28, 0.1.29, 0.1.33, 0.1.34, 0.1.35, 0.1.36, 0.1.37, 0.1.38, 0.1.43, 0.1.44, 0.1.45, 0.1.46, 0.1.47, 0.2.0, 0.2.1, 0.2.2, 0.3.0, 0.3.1, 0.3.2, 0.3.3, 0.3.4, 0.3.5, 0.3.6, 0.3.7, 0.3.8, 0.3.9, 0.3.10, 0.3.11, 0.3.12, 0.3.13, 0.3.14, 0.3.15, 0.3.16, 0.3.17, 0.4.0, 0.4.1, 0.4.2, 0.4.3, 0.5.0, 0.5.1, 0.5.2, 0.5.3, 0.5.4, 0.5.5, 0.5.6, 0.6.1, 0.6.2, 0.6.3, 0.6.4, 0.6.5, 0.6.6, 0.6.7, 0.6.8, 0.6.9, 0.6.10, 0.6.11, 0.6.12, 0.6.13, 0.6.14, 0.7.0, 0.7.1, 0.7.2, 0.7.3, 0.7.4, 0.7.5, 0.7.6, 0.7.7, 0.7.8, 0.8.0, 0.8.1, 0.8.2, 0.8.3, 0.8.4, 0.8.5, 0.9.0, 0.9.1, 0.9.2, 0.9.3, 0.10.0, 0.10.1, 0.10.2, 0.10.3, 0.10.4, 0.10.5, 0.10.6, 0.10.7, 1.0.0, 1.0.1, 1.1.0, 1.1.1, 1.1.2, 1.1.3, 1.2.0, 1.2.1, 1.3.0, 1.3.1, 1.3.2, 1.3.3, 1.3.4, 1.3.5, 1.3.6, 1.3.7, 1.4.0, 1.4.1, 1.4.2, 1.4.3, 1.4.4, 1.4.5, 1.4.6, 1.4.7, 1.5.0, 1.6.0, 1.6.1, 1.6.2, 1.6.3, 1.7.0, 1.7.1, 1.8.1, 1.9.0, 1.9.1, 1.9.2, 1.9.3, 1.9.4, 1.9.5, 1.9.6, 1.10.0, 1.11.0, 1.11.1, 1.12.0, 1.12.1, 1.12.2, 1.12.3, 1.12.4, 1.12.5, 1.13.0, 1.13.1, 2.0.0, 2.1.0, 2.1.1, 2.1.2, 2.1.3, 2.1.4, 2.1.5, 2.1.6, 2.1.7, 2.1.8, 2.1.9, 2.1.10, 2.1.11, 2.1.12, 2.1.13, 2.2.0rc1, 2.2.0rc2, 2.2.0)
  ERROR: No matching distribution found for Flask-AppBuilder==2.3.4 (from -c https://raw.githubusercontent.com/apache/airflow/constraints-1.10.12/constraints-3.6.txt (line 4))
  </code></pre>
  <p>and without them</p>
  <pre><code>ERROR: Could not find a version that satisfies the requirement pandas==1.1.0 (from -c https://raw.githubusercontent.com/apache/airflow/constraints-1.10.12/constraints-3.6.txt (line 205)) (from versions: 0.1, 0.2b0, 0.2b1, 0.2, 0.3.0b0, 0.3.0b2, 0.3.0, 0.4.0, 0.4.1, 0.4.2, 0.4.3, 0.5.0, 0.6.0, 0.6.1, 0.7.0rc1, 0.7.0, 0.7.1, 0.7.2, 0.7.3, 0.8.0rc1, 0.8.0rc2, 0.8.0, 0.8.1, 0.9.0, 0.9.1, 0.10.0, 0.10.1, 0.11.0, 0.12.0, 0.13.0, 0.13.1, 0.14.0, 0.14.1, 0.15.0, 0.15.1, 0.15.2, 0.16.0, 0.16.1, 0.16.2, 0.17.0, 0.17.1, 0.18.0, 0.18.1, 0.19.0rc1, 0.19.0, 0.19.1, 0.19.2, 0.20.0rc1, 0.20.0, 0.20.1, 0.20.2, 0.20.3, 0.21.0rc1, 0.21.0, 0.21.1, 0.22.0, 0.23.0rc2, 0.23.0, 0.23.1, 0.23.2, 0.23.3, 0.23.4, 0.24.0rc1, 0.24.0, 0.24.1, 0.24.2)
  ERROR: No matching distribution found for pandas==1.1.0 (from -c https://raw.githubusercontent.com/apache/airflow/constraints-1.10.12/constraints-3.6.txt (line 205))
  WARNING: You are using pip version 20.2.4; however, version 20.3.1 is available.
  </code></pre>