diff --git a/hgext/show.py b/hgext/show.py
--- a/hgext/show.py
+++ b/hgext/show.py
@@ -45,6 +45,7 @@
     registrar,
     revset,
     revsetlang,
+    scmutil,
 )
 
 # Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
@@ -447,8 +448,10 @@
     if not revs:
         return minlen
     # don't use filtered repo because it's slow. see templater.shortest().
-    cl = repo.unfiltered().changelog
-    return max(len(cl.shortest(hex(cl.node(r)), minlen)) for r in revs)
+    cl = repo.changelog
+    return max(len(scmutil.shortesthexnodeidprefix(repo.unfiltered(),
+                                                   hex(cl.node(r)),
+                                                   minlen)) for r in revs)
 
 # Adjust the docstring of the show command so it shows all registered views.
 # This is a bit hacky because it runs at the end of module load. When moved
diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -1500,44 +1500,6 @@
 
         raise LookupError(id, self.indexfile, _('no match found'))
 
-    def shortest(self, hexnode, minlength=1):
-        """Find the shortest unambiguous prefix that matches hexnode."""
-        def isvalid(test):
-            try:
-                if self._partialmatch(test) is None:
-                    return False
-
-                try:
-                    i = int(test)
-                    # if we are a pure int, then starting with zero will not be
-                    # confused as a rev; or, obviously, if the int is larger
-                    # than the value of the tip rev
-                    if test[0] == '0' or i > len(self):
-                        return True
-                    return False
-                except ValueError:
-                    return True
-            except error.RevlogError:
-                return False
-            except error.WdirUnsupported:
-                # single 'ff...' match
-                return True
-
-        shortest = hexnode
-        startlength = max(6, minlength)
-        length = startlength
-        while True:
-            test = hexnode[:length]
-            if isvalid(test):
-                shortest = test
-                if length == minlength or length > startlength:
-                    return shortest
-                length -= 1
-            else:
-                length += 1
-                if len(shortest) <= length:
-                    return shortest
-
     def cmp(self, node, text):
         """compare text with a given file revision
 
diff --git a/mercurial/scmutil.py b/mercurial/scmutil.py
--- a/mercurial/scmutil.py
+++ b/mercurial/scmutil.py
@@ -443,6 +443,46 @@
     repo.changelog.rev(node)  # make sure node isn't filtered
     return node
 
+def shortesthexnodeidprefix(repo, hexnode, minlength=1):
+    """Find the shortest unambiguous prefix that matches hexnode."""
+    cl = repo.changelog
+    def isvalid(test):
+        try:
+            if cl._partialmatch(test) is None:
+                return False
+
+            try:
+                i = int(test)
+                # if we are a pure int, then starting with zero will not be
+                # confused as a rev; or, obviously, if the int is larger
+                # than the value of the tip rev
+                if test[0] == '0' or i > len(cl):
+                    return True
+                return False
+            except ValueError:
+                return True
+        except error.RevlogError:
+            return False
+        except error.WdirUnsupported:
+            # single 'ff...' match
+            return True
+
+    shortest = hexnode
+    startlength = max(6, minlength)
+    length = startlength
+    while True:
+        test = hexnode[:length]
+        if isvalid(test):
+            shortest = test
+            if length == minlength or length > startlength:
+                return shortest
+            length -= 1
+        else:
+            length += 1
+            if len(shortest) <= length:
+                return shortest
+
+
 def isrevsymbol(repo, symbol):
     """Checks if a symbol exists in the repo.
 
diff --git a/mercurial/templatefuncs.py b/mercurial/templatefuncs.py
--- a/mercurial/templatefuncs.py
+++ b/mercurial/templatefuncs.py
@@ -590,8 +590,8 @@
     # _partialmatch() of filtered changelog could take O(len(repo)) time,
     # which would be unacceptably slow. so we look for hash collision in
     # unfiltered space, which means some hashes may be slightly longer.
-    cl = context.resource(mapping, 'ctx')._repo.unfiltered().changelog
-    return cl.shortest(node, minlength)
+    repo = context.resource(mapping, 'ctx')._repo
+    return scmutil.shortesthexnodeidprefix(repo.unfiltered(), node, minlength)
 
 @templatefunc('strip(text[, chars])')
 def strip(context, mapping, args):