Better fix for kombu is to unpin it and modify makefile

Makefile

@@ -113,10 +113,10 @@ endif
 	@echo "--> Updating Python requirements"
 	pip install --upgrade pip
 	pip install --upgrade pip-tools
+	pip-compile --output-file requirements.txt requirements.in -U --no-index
 	pip-compile --output-file requirements-docs.txt requirements-docs.in -U --no-index
 	pip-compile --output-file requirements-dev.txt requirements-dev.in -U --no-index
 	pip-compile --output-file requirements-tests.txt requirements-tests.in -U --no-index
-	pip-compile --output-file requirements.txt requirements.in -U --no-index
 	@echo "--> Done updating Python requirements"
 	@echo "--> Removing python-ldap from requirements-docs.txt"
 	grep -v "python-ldap" requirements-docs.txt > tempreqs && mv tempreqs requirements-docs.txt

requirements-docs.txt

@@ -49,7 +49,7 @@ jinja2==2.10
 jmespath==0.9.3
 josepy==1.1.0
 jsonlines==1.2.0
-kombu==4.2.1
+kombu==4.2.2.post1
 lockfile==0.12.2
 mako==1.0.7
 markupsafe==1.1.0

requirements.in

@@ -25,7 +25,6 @@ future
 gunicorn
 inflection
 jinja2
-kombu<=4.2.2 # Kombu 4.2.2 breaks requirements
 lockfile
 marshmallow-sqlalchemy
 marshmallow

requirements.txt

@@ -46,7 +46,7 @@ jinja2==2.10
 jmespath==0.9.3           # via boto3, botocore
 josepy==1.1.0             # via acme
 jsonlines==1.2.0          # via cloudflare
-kombu==4.2.1
+kombu==4.2.2.post1        # via celery
 lockfile==0.12.2
 mako==1.0.7               # via alembic
 markupsafe==1.1.0         # via jinja2, mako