diff --git a/mercurial/debugcommands.py b/mercurial/debugcommands.py
--- a/mercurial/debugcommands.py
+++ b/mercurial/debugcommands.py
@@ -1947,6 +1947,7 @@
       _('print parsed tree at the given stage'), _('NAME')),
      ('', 'no-optimized', False, _('evaluate tree without optimization')),
      ('', 'verify-optimized', False, _('verify optimized result')),
+     ('', 'check-ordering', False, _('try to detect ordering issues')),
      ],
     ('REVSPEC'))
 def debugrevspec(ui, repo, expr, **opts):
@@ -2007,6 +2008,25 @@
             ui.write(revsetlang.prettyformat(tree), "\n")
             printedtree = tree
 
+    if opts['check_ordering']:
+        problematic = []
+        for name in ('defineorder', 'followorder'):
+            m = revset.makematcher(tree, order=getattr(revset, name))
+            s = smartset.fullreposet(repo)
+            revs1 = list(m(repo, s))
+            s.reverse()
+            revs2 = list(m(repo, s))
+            if len(revs1) <= 1:
+                ui.write(('ordering: cannot detect issues if len(revs) <= 1\n'))
+                break
+            if ((revs1 == revs2 and name == 'followorder') or
+                (revs1 != revs2 and name == 'defineorder')):
+                problematic.append(name)
+        if problematic:
+            ui.write(('ordering: %s not respected\n')
+                     % (' and '.join(problematic)))
+            return 1
+
     if opts['verify_optimized']:
         arevs = revset.makematcher(treebystage['analyzed'])(repo)
         brevs = revset.makematcher(treebystage['optimized'])(repo)
diff --git a/tests/test-completion.t b/tests/test-completion.t
--- a/tests/test-completion.t
+++ b/tests/test-completion.t
@@ -282,7 +282,7 @@
   debugrebuildfncache: 
   debugrename: rev
   debugrevlog: changelog, manifest, dir, dump
-  debugrevspec: optimize, show-revs, show-set, show-stage, no-optimized, verify-optimized
+  debugrevspec: optimize, show-revs, show-set, show-stage, no-optimized, verify-optimized, check-ordering
   debugsetparents: 
   debugssl: 
   debugsub: rev
diff --git a/tests/test-revset-ordering.t b/tests/test-revset-ordering.t
new file mode 100644
--- /dev/null
+++ b/tests/test-revset-ordering.t
@@ -0,0 +1,75 @@
+Check if revset predicates respect order as told
+
+  $ check() {
+  >   hg debugrevspec --no-show-revs --check-ordering "$@"; :
+  > }
+  $ cat >> $HGRCPATH <<EOF
+  > [extensions]
+  > drawdag=$TESTDIR/drawdag.py
+  > EOF
+
+  $ hg init repo1
+  $ cd repo1
+  $ hg debugdrawdag <<'EOS'
+  >  C E  # B/A = A1
+  >  |/|  # C/A = A2
+  >  B D  # D/A = A3
+  >  |/|  # E/A = A4
+  >  A Z
+  > EOS
+
+  $ for i in A B D; do
+  >   hg bookmark -ir $i book-$i
+  > done
+
+  $ check '3+1+2'
+  $ check '(3+1+2)-1'
+  $ check '(3+1+2) & (1+3+4)'
+  $ check 'A::E'
+  $ check 'E:A'
+  $ check 'E % C'
+  $ check 'not E'
+  ordering: defineorder not respected
+
+  $ check 'adds("*")'
+  ordering: defineorder not respected
+  $ check 'all()'
+  ordering: defineorder not respected
+  $ check 'ancestors(E)'
+  $ check 'author(test)'
+  ordering: defineorder not respected
+  $ hg bisect --good A -q
+  $ hg bisect --bad E -q >/dev/null
+  $ check 'bisect(untested)'
+  ordering: defineorder not respected
+  $ check 'bookmark()'
+  ordering: defineorder not respected
+  $ check 'branch(default)'
+  ordering: defineorder not respected
+  $ check 'children(A)'
+  ordering: defineorder not respected
+  $ check 'contains(A)'
+  ordering: defineorder not respected
+  $ check 'date("0 0")'
+  ordering: defineorder not respected
+  $ check 'draft()'
+  $ check 'file("*")'
+  ordering: defineorder not respected
+  $ check 'filelog("A")'
+  ordering: defineorder not respected
+  $ check 'grep("A")'
+  ordering: defineorder not respected
+  $ check 'head()'
+  $ check 'heads(E+C)'
+  ordering: followorder not respected
+  $ check 'merge()'
+  ordering: defineorder not respected
+  $ check 'p1(B+E+D)'
+  $ check 'p2(B+E+D)'
+  $ check 'parents(E)'
+  ordering: defineorder not respected
+  $ check 'reverse(B+E+D)'
+  $ check 'roots(B+E+D)'
+  $ check 'sort(all())'
+  $ check 'tagged()'
+  ordering: defineorder not respected