Make each DNS plugin respect EXCLUDE_CERTBOT_DEPS (#8117)

* Don't include certbot deps when EXCLUDE_CERTBOT_DEPS is set

* import os

certbot-dns-digitalocean/setup.py

@@ -1,4 +1,5 @@
 from distutils.version import LooseVersion
+import os
 import sys
 
 from setuptools import __version__ as setuptools_version
@@ -11,14 +12,21 @@ version = '1.6.0.dev0'
 # Remember to update local-oldest-requirements.txt when changing the minimum
 # acme/certbot version.
 install_requires = [
-    'acme>=0.29.0',
-    'certbot>=1.1.0',
     'python-digitalocean>=1.11',
     'setuptools',
     'six',
     'zope.interface',
 ]
 
+if not os.environ.get('EXCLUDE_CERTBOT_DEPS'):
+    install_requires.extend([
+        'acme>=0.29.0',
+        'certbot>=1.1.0',
+    ])
+elif 'bdist_wheel' in sys.argv[1:]:
+    raise RuntimeError('Unset EXCLUDE_CERTBOT_DEPS when building wheels '
+                       'to include certbot dependencies.')
+
 setuptools_known_environment_markers = (LooseVersion(setuptools_version) >= LooseVersion('36.2'))
 if setuptools_known_environment_markers:
     install_requires.append('mock ; python_version < "3.3"')