--- a/mercurial/dispatch.py	Sat Jun 24 23:09:21 2017 -0400
+++ b/mercurial/dispatch.py	Sat Jun 24 02:39:20 2017 +0900
@@ -30,17 +30,12 @@
     error,
     extensions,
     fancyopts,
-    fileset,
     help,
     hg,
     hook,
     profiling,
     pycompat,
-    revset,
     scmutil,
-    templatefilters,
-    templatekw,
-    templater,
     ui as uimod,
     util,
 )
@@ -727,22 +722,6 @@
 
 _loaded = set()
 
-# list of (objname, loadermod, loadername) tuple:
-# - objname is the name of an object in extension module, from which
-#   extra information is loaded
-# - loadermod is the module where loader is placed
-# - loadername is the name of the function, which takes (ui, extensionname,
-#   extraobj) arguments
-extraloaders = [
-    ('cmdtable', commands, 'loadcmdtable'),
-    ('colortable', color, 'loadcolortable'),
-    ('filesetpredicate', fileset, 'loadpredicate'),
-    ('revsetpredicate', revset, 'loadpredicate'),
-    ('templatefilter', templatefilters, 'loadfilter'),
-    ('templatefunc', templater, 'loadfunction'),
-    ('templatekeyword', templatekw, 'loadkeyword'),
-]
-
 def _dispatch(req):
     args = req.args
     ui = req.ui
@@ -770,19 +749,11 @@
         # reposetup. Programs like TortoiseHg will call _dispatch several
         # times so we keep track of configured extensions in _loaded.
         extensions.loadall(lui)
-        exts = [ext for ext in extensions.extensions() if ext[0] not in _loaded]
         # Propagate any changes to lui.__class__ by extensions
         ui.__class__ = lui.__class__
 
         # (uisetup and extsetup are handled in extensions.loadall)
 
-        for name, module in exts:
-            for objname, loadermod, loadername in extraloaders:
-                extraobj = getattr(module, objname, None)
-                if extraobj is not None:
-                    getattr(loadermod, loadername)(ui, name, extraobj)
-            _loaded.add(name)
-
         # (reposetup is handled in hg.repository)
 
         addaliases(lui, commands.table)

--- a/mercurial/extensions.py	Sat Jun 24 23:09:21 2017 -0400
+++ b/mercurial/extensions.py	Sat Jun 24 02:39:20 2017 +0900
@@ -243,6 +243,43 @@
     # entries could result in double execution. See issue4646.
     _aftercallbacks.clear()
 
+    # delay importing avoids cyclic dependency (especially commands)
+    from . import (
+        color,
+        commands,
+        fileset,
+        revset,
+        templatefilters,
+        templatekw,
+        templater,
+    )
+
+    # list of (objname, loadermod, loadername) tuple:
+    # - objname is the name of an object in extension module,
+    #   from which extra information is loaded
+    # - loadermod is the module where loader is placed
+    # - loadername is the name of the function,
+    #   which takes (ui, extensionname, extraobj) arguments
+    extraloaders = [
+        ('cmdtable', commands, 'loadcmdtable'),
+        ('colortable', color, 'loadcolortable'),
+        ('filesetpredicate', fileset, 'loadpredicate'),
+        ('revsetpredicate', revset, 'loadpredicate'),
+        ('templatefilter', templatefilters, 'loadfilter'),
+        ('templatefunc', templater, 'loadfunction'),
+        ('templatekeyword', templatekw, 'loadkeyword'),
+    ]
+
+    for name in _order[newindex:]:
+        module = _extensions[name]
+        if not module:
+            continue # loading this module failed
+
+        for objname, loadermod, loadername in extraloaders:
+            extraobj = getattr(module, objname, None)
+            if extraobj is not None:
+                getattr(loadermod, loadername)(ui, name, extraobj)
+
 def afterloaded(extension, callback):
     '''Run the specified function after a named extension is loaded.
 

--- a/tests/test-extension.t	Sat Jun 24 23:09:21 2017 -0400
+++ b/tests/test-extension.t	Sat Jun 24 02:39:20 2017 +0900
@@ -77,15 +77,25 @@
   >     print "3) %s extsetup" % name
   > def reposetup(ui, repo):
   >    print "4) %s reposetup" % name
+  > 
+  > # custom predicate to check registration of functions at loading
+  > from mercurial import (
+  >     registrar,
+  >     smartset,
+  > )
+  > revsetpredicate = registrar.revsetpredicate()
+  > @revsetpredicate(name, safe=True) # safe=True for query via hgweb
+  > def custompredicate(repo, subset, x):
+  >     return smartset.baseset([r for r in subset if r in {0}])
   > EOF
 
   $ cp foo.py bar.py
   $ echo 'foo = foo.py' >> $HGRCPATH
   $ echo 'bar = bar.py' >> $HGRCPATH
 
-Command with no output, we just want to see the extensions loaded:
+Check normal command's load order of extensions and registration of functions
 
-  $ hg paths
+  $ hg log -r "foo() and bar()" -q
   1) foo imported
   1) bar imported
   2) foo uisetup
@@ -94,8 +104,9 @@
   3) bar extsetup
   4) foo reposetup
   4) bar reposetup
+  0:c24b9ac61126
 
-Check hgweb's load order:
+Check hgweb's load order of extensions and registration of functions
 
   $ cat > hgweb.cgi <<EOF
   > #!$PYTHON
@@ -118,6 +129,14 @@
   4) foo reposetup
   4) bar reposetup
 
+(check that revset predicate foo() and bar() are available)
+
+  $ REQUEST_METHOD='GET' PATH_INFO='/shortlog' SCRIPT_NAME='' \
+  >     QUERY_STRING='rev=foo() and bar()' \
+  >     SERVER_PORT='80' SERVER_NAME='localhost' python hgweb.cgi \
+  >     | grep '<a href="/rev/[0-9a-z]*">'
+     <a href="/rev/c24b9ac61126">add file</a>
+
   $ echo 'foo = !' >> $HGRCPATH
   $ echo 'bar = !' >> $HGRCPATH