Don't use unevaluate for 1

sumpy/tools.py

@@ -58,7 +58,9 @@ def mi_factorial(mi):
 def mi_power(vector, mi, evaluate=True):
     result = 1
     for mi_i, vec_i in zip(mi, vector):
-        if evaluate:
+        if mi_i == 1:
+            result *= vec_i
+        elif evaluate:
             result *= vec_i**mi_i
         else:
             result *= sym.unevaluated_pow(vec_i, mi_i)