With mutating indices
:(. Without looks hard (see stable in-place mergesort).
a = [8, 6, 7, 5, 3, 0, 9]
indices = [3, 6, 2, 4, 0, 1, 5]
for i in xrange(len(a)):
x = a[i]
j = i
while True:
k = indices[j]
indices[j] = j
if k == i:
break
a[j] = a[k]
j = k
a[j] = x
print a