diff --git a/hg b/hg
--- a/hg
+++ b/hg
@@ -26,20 +26,12 @@
         libdir = os.path.abspath(libdir)
     sys.path.insert(0, libdir)
 
-# enable importing on demand to reduce startup time
 try:
-    if sys.version_info[0] < 3 or sys.version_info >= (3, 6):
-        import hgdemandimport; hgdemandimport.enable()
+    import mercurial.dispatch
 except ImportError:
     sys.stderr.write("abort: couldn't find mercurial libraries in [%s]\n" %
                      ' '.join(sys.path))
     sys.stderr.write("(check your install and PYTHONPATH)\n")
     sys.exit(-1)
 
-import mercurial.util
-import mercurial.dispatch
-
-for fp in (sys.stdin, sys.stdout, sys.stderr):
-    mercurial.util.setbinary(fp)
-
 mercurial.dispatch.run()
diff --git a/mercurial/dispatch.py b/mercurial/dispatch.py
--- a/mercurial/dispatch.py
+++ b/mercurial/dispatch.py
@@ -75,6 +75,8 @@
 
 def run():
     "run the command in sys.argv"
+    _enabledemandimport()
+    _setbinary()
     req = request(pycompat.sysargv[1:])
     err = None
     try:
@@ -92,6 +94,16 @@
         req.ui.ferr.flush()
     sys.exit(status & 255)
 
+def _enabledemandimport():
+    """enable importing on demand to reduce startup time"""
+    if sys.version_info[0] < 3 or sys.version_info >= (3, 6):
+        import hgdemandimport; hgdemandimport.enable()
+
+def _setbinary():
+    """use binary mode for standard streams"""
+    for fp in (sys.stdin, sys.stdout, sys.stderr):
+        util.setbinary(fp)
+
 def _getsimilar(symbols, value):
     sim = lambda x: difflib.SequenceMatcher(None, value, x).ratio()
     # The cutoff for similarity here is pretty arbitrary. It should