Move black to separate script

.circleci/config.yml

@@ -11,3 +11,4 @@ jobs:
             - run: env/bin/pip install -e .
             - run: env/bin/pip install -r dev-requirements.txt
             - run: ./scripts/test.sh
+            - run: ./scripts/black.sh

dev-requirements.txt

@@ -1,4 +1,3 @@
-black==18.9b0
 flake8==3.6.0
 flake8-comprehensions==1.4.1
 flake8-mutable==1.2.0

scripts/black.sh

@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+
+set -e
+
+export PATH=env/bin:${PATH}
+
+pip install black==18.9b0
+
+black tests ipc_unix setup.py --check

scripts/test.sh

@@ -6,7 +6,6 @@ export PATH=env/bin:${PATH}
 
 nose2 $@ -C --coverage ipc_unix --verbose
 
-black tests ipc_unix setup.py --check
 flake8 ipc_unix tests setup.py --ignore=E128,E501
 isort -rc -c ipc_unix tests setup.py
 mypy --strict-optional ipc_unix tests