--- a/mercurial/hgweb/webcommands.py	Wed Mar 29 12:14:20 2017 -0700
+++ b/mercurial/hgweb/webcommands.py	Thu Mar 30 21:40:10 2017 +0200
@@ -998,7 +998,8 @@
         basectx = ctx.p1()
         path = fctx.path()
         return webutil.diffs(web, tmpl, ctx, basectx, [path], diffstyle,
-                             linerange=linerange)
+                             linerange=linerange,
+                             lineidprefix='%s-' % ctx.hex()[:12])
 
     linerange = None
     if lrange is not None: