templater: do not use index.partialmatch() directly to calculate shortest() cl.index.partialmatch() isn't a drop-in replacement for cl._partialmatch(). It has no knowledge about hidden revisions, and it raises ValueError if a node shorter than 4 chars is given. Instead, use index.partialmatch() through cl._partialmatch(), which has no such problems and gives the identical result with/without --pure. The test output was sampled with --pure without this patch, which shows the most correct result. However, we'll need to switch to using an unfiltered changelog because _partialmatch() of a filtered changelog can be an order of magnitude slower. (with hidden revisions) % hg log -R hg-committed -r0:20000 -T '{node|shortest}\n' --time > /dev/null (.^) time: real 1.530 secs (user 1.480+0.000 sys 0.040+0.000) (.) time: real 43.080 secs (user 43.060+0.000 sys 0.030+0.000)

--- a/mercurial/templater.py	Wed Oct 26 22:50:06 2016 +0900
+++ b/mercurial/templater.py	Sun Oct 23 14:05:23 2016 +0900
@@ -840,13 +840,8 @@
     cl = mapping['ctx']._repo.changelog
     def isvalid(test):
         try:
-            try:
-                cl.index.partialmatch(test)
-            except AttributeError:
-                # Pure mercurial doesn't support partialmatch on the index.
-                # Fallback to the slow way.
-                if cl._partialmatch(test) is None:
-                    return False
+            if cl._partialmatch(test) is None:
+                return False
 
             try:
                 i = int(test)