Merge pull request cherrypy#2011 from radez/issue1973-2

This patch adds a dependency on `importlib_metadata` in runtime conditionally, when `importlib.metadata` is unavailable.
It also starts using it as a fallback in the Sphinx config and drops unnecessary import suppression from the fallback branch.

cherrypy/__init__.py

@@ -60,11 +60,8 @@
     import importlib.metadata as importlib_metadata
 except ImportError:
     # fall back for python <= 3.7
-    # can simply pass when py 3.6/3.7 no longer supported
-    try:
-        import importlib_metadata
-    except ImportError:
-        pass
+    # This try/except can be removed with py <= 3.7 support
+    import importlib_metadata
 
 from threading import local as _local
 

docs/conf.py

@@ -16,6 +16,13 @@
 import importlib
 import sys
 
+try:
+    import importlib.metadata as importlib_metadata
+except ImportError:
+    # fall back for python <= 3.7
+    # This try/except can be removed with py <= 3.7 support
+    import importlib_metadata
+
 assert sys.version_info > (3, 5), 'Python 3 required to build docs'
 
 
@@ -41,7 +48,7 @@ def get_supported_pythons(classifiers):
 
 custom_sphinx_theme = try_import('alabaster')
 
-prj_meta = importlib.metadata.metadata('cherrypy')
+prj_meta = importlib_metadata.metadata('cherrypy')
 prj_author = prj_meta['Author']
 prj_license = prj_meta['License']
 prj_description = prj_meta['Description']

setup.py

@@ -70,6 +70,7 @@
         'more_itertools',
         'zc.lockfile',
         'jaraco.collections',
+        'importlib-metadata; python_version<="3.7"',
     ],
     extras_require={
         'docs': [