diff -r 7bf48bc7de23 -r 7002bb17cc5e mercurial/posix.py
--- a/mercurial/posix.py	Mon May 14 12:56:43 2012 +0200
+++ b/mercurial/posix.py	Mon May 14 13:25:42 2012 +0100
@@ -409,10 +409,13 @@
                     continue
                 if not os.isatty(fd):
                     continue
-                arri = fcntl.ioctl(fd, termios.TIOCGWINSZ, '\0' * 8)
-                width = array.array('h', arri)[1]
-                if width > 0:
-                    return width
+                try:
+                    arri = fcntl.ioctl(fd, termios.TIOCGWINSZ, '\0' * 8)
+                    width = array.array('h', arri)[1]
+                    if width > 0:
+                        return width
+                except AttributeError:
+                    pass
             except ValueError:
                 pass
             except IOError, e: