Applied @blueyed review comments

doc/en/conf.py

@@ -112,16 +112,18 @@
 # A list of ignored prefixes for module index sorting.
 # modindex_common_prefix = []
 
-# A list of regular expressions that match URIs that should not be checked when doing a linkcheck
-# see https://www.sphinx-doc.org/en/master/usage/configuration.html#options-for-the-linkcheck-builder
+# A list of regular expressions that match URIs that should not be checked when
+# doing a linkcheck.
 linkcheck_ignore = [
     "https://github.com/numpy/numpy/blob/master/doc/release/1.16.0-notes.rst#new-deprecations",
     "https://blogs.msdn.microsoft.com/bharry/2017/06/28/testing-in-a-cloud-delivery-cadence/",
     "http://pythontesting.net/framework/pytest-introduction/",
+    r"https://github.com/pytest-dev/pytest/issues/\d+",
+    r"https://github.com/pytest-dev/pytest/pull/\d+",
 ]
 
-# The number of worker threads to use when checking links
-linkcheck_workers = 20
+# The number of worker threads to use when checking links (default=5).
+linkcheck_workers = 5
 
 
 # -- Options for HTML output ---------------------------------------------------

tox.ini

@@ -72,7 +72,7 @@ usedevelop = True
 changedir = doc/en
 deps = -r{toxinidir}/doc/en/requirements.txt
 commands =
-    sphinx-build -q -W --keep-going -b linkcheck . _build
+    sphinx-build -W --keep-going -b linkcheck . _build
 
 [testenv:doctesting]
 basepython = python3