### RandomLinearCode on non-prime fields fail ... sometimes.

Consider the following piece of code:

```
C=codes.RandomLinearCode(4,2,GF(16,'b'))
C.minimum_distance()
```

About half of the time, it fails with error

```
TypeError: unable to coerce from a finite field other than the prime subfield
```

I'd understand if SAGE could only compute the minimum distance for codes over primes fields, what has me confused is the fact that sometimes it can, sometimes it can't. Any clues as to what is going on here?