Use -U in the pip install for py-geth if missing geth binary:

- This will force pip to install the latest version of py-geth,
  even if another version is already installed. If the test
  fixture has just been updated, this is a requirement.

Author: fselmo

.circleci/config.yml

@@ -77,7 +77,7 @@ geth_steps: &geth_steps
               sudo apt-get install -y build-essential
               pygeth_version=$(python web3/scripts/parse_pygeth_version.py)
               echo "installing py-geth$pygeth_version"
-              pip install --user "py-geth$pygeth_version"
+              pip install -U --user "py-geth$pygeth_version"
               python -m geth.install v<< pipeline.parameters.geth_version >>
             fi
             sudo ln -s /home/circleci/.py-geth/geth-v<< pipeline.parameters.geth_version >>/bin/geth /usr/local/bin/geth

newsfragments/3637.internal.rst

@@ -0,0 +1 @@
+Use ``-U`` to install latest `py-geth` version for CI geth steps. This is usually a requirement if we're missing the binary for the newly-generated fixture geth version.