Blacklist `sphinxprettysearchresults` in the extension registry (#11926)

CHANGES.rst

@@ -72,6 +72,9 @@ Bugs fixed
   Patch by Colin Marquardt.
 * #11598: Do not use query components in URLs for assets in EPUB rendering.
   Patch by David Runge.
+* #11925: Blacklist the ``sphinxprettysearchresults`` extension; the functionality
+  it provides was merged into Sphinx v2.0.0.
+  Patch by James Addison.
 
 Testing
 -------

sphinx/registry.py

@@ -52,6 +52,7 @@ logger = logging.getLogger(__name__)
 # Values are Sphinx version that merge the extension.
 EXTENSION_BLACKLIST = {
     "sphinxjp.themecore": "1.2",
+    "sphinxprettysearchresults": "2.0.0",
 }