Fixed failing test with tolerance (shows there was no real problem).

Checked the numbers with code like : https://gist.github.com/pp-mo/9979539
Results:
```
    values:     min=     243.268,     max=     1453.17,    mean=     409.069,  median=     319.299
     diffs:     min= -0.00012207,     max=  0.00012207,    mean=-2.16005e-07,  median=           0
 abs-diffs:     min=           0,     max=  0.00012207,    mean= 9.30482e-06,  median=           0
 rel-diffs:     min=           0,     max= 1.01501e-07,    mean= 6.86106e-09,  median=           0
```

So, no problem really -- the absolute and relative differences are really very small.