slate pidgin woes

I'm trying to make some changes to the slate pidgin code to help make
porting the VM to my 64 bit machine easier. I probably did a few too
many search/replaces but basically I'm getting this error:

Generating function PSObject_isImmutable

Generating function PSObject_restrictsDelegation

Generating function PSObject_addSlotNamed_valued_at_

The following condition was signaled:
Error: A method translation wasn't found for copyBytes:into:.

The following restarts are available:
0)      Abort evaluation of expression
1)      Quit Slate

Enter 'help.' for instructions.
Debug [0..1]: up.
[tryHandlers]

the method translation searcher is:

g@(C SimpleGenerator traits) generateCFor: selector@(Symbol traits) on: arguments
[...]

g: ("SimpleGenerator" currentColumn: 0. currentLine: 0. level: 0. columnsPerLine: 1000.
    original: ("Stream" ...). inlining: True. asserting: False. verbose: False. useSymbolicConstants: True.
    useRightShiftForDivide: True. generateDeadCode: False. methodCalls: {"Bag" ...}.