ancestor.deepest: ignore ninteresting while building result (issue3984)

ninteresting indicates the number of non-zero elements in the interesting
array, not the number of elements in the final list. Since elements in
interesting can stand for more than one gca, limiting the number of results to
ninteresting is an error.

Tests for issue3984 are included.

mercurial/parsers.c

@@ -1388,8 +1388,7 b' static PyObject *find_deepest(indexObjec'
 	if (dict == NULL)
 		goto bail;
 
-	j = ninteresting;
-	for (i = 0; i < revcount && j > 0; i++) {
+	for (i = 0; i < revcount; i++) {
 		PyObject *key;
 
 		if ((final & (1 << i)) == 0)
@@ -1403,7 +1402,6 b' static PyObject *find_deepest(indexObjec'
 			Py_DECREF(Py_None);
 			goto bail;
 		}
-		j -= 1;
 	}
 
 	keys = PyDict_Keys(dict);

tests/test-ancestor.py

@@ -1,4 +1,4 b''
-from mercurial import ancestor
+from mercurial import ancestor, commands, hg, ui, util
 
 # graph is a dict of child->parent adjacency lists for this graph:
 # o  13
@@ -101,6 +101,36 b' def test_lazyancestors():'
     s = genlazyancestors([11, 13], stoprev=6, inclusive=True)
     printlazyancestors(s, [11, 13, 7, 9, 8, 3, 6, 4, 1, -1, 0])
 
+
+# The C gca algorithm requires a real repo. These are textual descriptions of
+# dags that have been known to be problematic.
+dagtests = [
+    '+2*2*2/*3/2',
+    '+3*3/*2*2/*4*4/*4/2*4/2*2',
+]
+def test_gca():
+    u = ui.ui()
+    for i, dag in enumerate(dagtests):
+        repo = hg.repository(u, 'gca%d' % i, create=1)
+        cl = repo.changelog
+        if not util.safehasattr(cl.index, 'ancestors'):
+            # C version not available
+            return
+
+        commands.debugbuilddag(u, repo, dag)
+        # Compare the results of the Python and C versions. This does not
+        # include choosing a winner when more than one gca exists -- we make
+        # sure both return exactly the same set of gcas.
+        for a in cl:
+            for b in cl:
+                cgcas = sorted(cl.index.ancestors(a, b))
+                pygcas = sorted(ancestor.ancestors(cl.parentrevs, a, b))
+                if cgcas != pygcas:
+                    print "test_gca: for dag %s, gcas for %d, %d:" % (dag, a, b)
+                    print "  C returned:      %s" % cgcas
+                    print "  Python returned: %s" % pygcas
+
 if __name__ == '__main__':
     test_missingancestors()
     test_lazyancestors()
+    test_gca()