Description of Drivers Ticket:

Drivers that already have OCSP tests running in Evergreen will need to update their Evergreen config files to install the flask requirement (via a newly added requirements file) instead of bottle.  e.g.:

-          ./venv/Scripts/pip3 install asn1crypto oscrypto bottle
+          ./venv/Scripts/pip3 install -r ${DRIVERS_TOOLS}/.evergreen/ocsp/mock-ocsp-responder-requirements.txt

[edit: per shane.harvey's suggestion, it would best to store the mock responder's requirements in drivers-evergreen-tools so that future updates to the mock responder's requirements will not require drivers changes]

Drivers that don't yet have OCSP tests running in Evergreen do not need to do anything, as such drivers will use flask from the get-go as  part their initial effort to get OCSP tests running in Evergreen. 

This change is needed due to: mongodb-labs/drivers-evergreen-tools#102 which fixes: mongodb-labs/drivers-evergreen-tools#99 and mongodb-labs/drivers-evergreen-tools#100 and includes changes from: https://jira.mongodb.org/browse/SERVER-46413
and mongodb/mongo#1351

 
See DRIVERS-977 for updated details.