mq: fix qnext when all remaining patches are guarded

When all remaining patches are guarded, qnext used to return the last of the
queue anyway.

hgext/mq.py

@@ -1757,9 +1757,9 b' class queue(object):'
             for i in xrange(start, len(self.series)):
                 p, reason = self.pushable(i)
                 if p:
-                    break
+                    return i
                 self.explainpushable(i)
-            return i
+            return len(self.series)
         if self.applied:
             p = self.applied[-1].name
             try:
@@ -2205,7 +2205,7 b' def top(ui, repo, **opts):'
 
 @command("qnext", seriesopts, _('hg qnext [-s]'))
 def next(ui, repo, **opts):
-    """print the name of the next patch
+    """print the name of the next pushable patch
 
     Returns 0 on success."""
     q = repo.mq

tests/test-mq-guards.t

@@ -107,6 +107,9 b' should skip c.patch'
   applying b.patch
   skipping c.patch - guarded by '-a'
   now at: b.patch
+  $ hg qnext
+  all patches applied
+  [1]
 
 should display b.patch
 

tests/test-mq.t

@@ -72,7 +72,7 b' help'
    qheader       print the header of the topmost or specified patch
    qimport       import a patch
    qnew          create a new patch
-   qnext         print the name of the next patch
+   qnext         print the name of the next pushable patch
    qpop          pop the current patch off the stack
    qprev         print the name of the previous patch
    qpush         push the next patch onto the stack