commit 917b505c86a70dda2191d380861af05becc03858
Author: Karim Belabas <Karim.Belabas@math.u-bordeaux1.fr>
Date:   Mon Mar 12 23:54:11 2012 +0100

    ispower(x < 0,, &n): n could have the wrong sign [#1302]

diff --git a/src/basemath/arith1.c b/src/basemath/arith1.c
index ded946b..5502ba5 100644
--- a/src/basemath/arith1.c
+++ b/src/basemath/arith1.c
@@ -1109,6 +1109,7 @@ Z_isanypower(GEN x, GEN *pty)
       *pty = gerepileuptoint(av, y);
       return k;
     }
+    if (pty) togglesign_safe(pty);
   }
   if (pty) *pty = gerepilecopy(av, *pty); else avma = av;
   return k;
diff --git a/src/test/32/ispower b/src/test/32/ispower
index bf4b6f0..84d8de7 100644
--- a/src/test/32/ispower
+++ b/src/test/32/ispower
@@ -1118,7 +1118,7 @@
 [2, 999]
 [6, 10]
 [3, -4]
-[3, 2]
-[3, 21218]
+[3, -2]
+[3, -21218]
 [3, -1/4]
-Total time spent: 3236
+Total time spent: 3012