diff -r 2cd5f1fac788 -r c93d046d4300 mercurial/dispatch.py
--- a/mercurial/dispatch.py	Sat Nov 17 19:11:45 2018 +0900
+++ b/mercurial/dispatch.py	Mon Nov 12 21:10:51 2018 +0900
@@ -866,6 +866,9 @@
         # Check abbreviation/ambiguity of shell alias.
         shellaliasfn = _checkshellalias(lui, ui, args)
         if shellaliasfn:
+            # no additional configs will be set, set up the ui instances
+            for ui_ in uis:
+                extensions.populateui(ui_)
             return shellaliasfn()
 
         # check for fallback encoding
@@ -948,6 +951,10 @@
             for ui_ in uis:
                 ui_.disablepager()
 
+        # configs are fully loaded, set up the ui instances
+        for ui_ in uis:
+            extensions.populateui(ui_)
+
         if options['version']:
             return commands.version_(ui)
         if options['help']: