Bug description: On starting the new SC 3.7 prerelease build on OSX 10.8 I get:
SCDoc: Indexing help-files...
ERROR: Message 'isPathSeparator' not understood.
RECEIVER:
nil
ARGS:

PROTECTED CALL STACK:
Meta_MethodError:new 0x114eae9c0
arg this = DoesNotUnderstandError
arg what = nil
arg receiver = nil
Meta_DoesNotUnderstandError:new 0x114eb0980
arg this = DoesNotUnderstandError
arg receiver = nil
arg selector = isPathSeparator
arg args = [ ]
Object:doesNotUnderstand 0x114a06440
arg this = nil
arg selector = isPathSeparator
arg args = nil
PathName:entries 0x115a16040
arg this = PathName()
var path =
PathName:folders 0x115a18000
arg this = PathName()
a FunctionDef 0x114da5840
sourceCode = ""
arg dir = PathName()
ArrayedCollection:do 0x115abc540
arg this = [ /Users/cere/Library/Application Support/SuperCollider/Extensions, /Library/Application Support/SuperCollider/Extensions, ]
arg function = a Function
var i = 2
Meta_SCDoc:helpSourceDirs 0x114da5300
arg this = SCDoc
var find = a Function
var rootPaths = [ /Users/cere/Library/Application Support/SuperCollider/Extensions, /Library/Application Support/SuperCollider/Extensions, ]
Meta_SCDoc:indexAllDocuments 0x114da0900
arg this = SCDoc
arg clearCache = false
var now = 1.248405106
var key = nil
var doc = nil
var nonHelpFiles = nil
var undocClasses = IdentitySet[ GrayNoise, TapN, StartUp, Error, TdefGui, AbstractPlayControl, SymbolArray, Plambda, Ppar, JITGui, CurveWarp, Int8Array, SinGrainIBF, SoftClipAmp, UHJ2B, ScaleInfo, Pen, BLBufRd, TouchResponder, PV_Cutoff, BusScopeSynth, OteyPiano, Switch1, Poll, DelayC, Function, Prout, QPen, FuncFilterPattern, BendResponder, AbstractIn, Rest, TabFileReader, CleanupStream, FoaDominateX, Pseg, Ref, DragView, FeatureSave, Pevent, SCViewHolder, BufGrain, PowerOfTwoBlock, CheapVerb, RMShelf, FFTSubbandPower, HDR, ...etc...
var additions = Dictionary[ ]
Meta_SCDoc:documents 0x114da5180
arg this = SCDoc
Meta_SCDoc:prepareHelpForURL 0x114da90c0
arg this = SCDoc
arg url = file:///Users/cere/Library/Application Support/SuperCollider/Help/Help.html
var path = /Users/cere/Library/Application Support/SuperCollider/Help/Help.html
var targetBasePath = /Users/cere/Library/Application Support/SuperCollider/Help
var pathIsCaseInsensitive = false
var subtarget = Help
var src = nil
var c = nil
var cmd = nil
var doc = nil
var destExist = true
var destMtime = 1430775913
var verpath = /Users/cere/Library/Application Support/SuperCollider/Help/version
a FunctionDef 0x114d01e40
sourceCode = ""
Function:prTry 0x11510ce80
arg this = a Function
var result = nil
var thread = a Routine
var next = nil
var wasInProtectedFunc = true

CALL STACK:
DoesNotUnderstandError:reportError 0x116c6d848
arg this =
< closed FunctionDef > 0x116beca58
arg error =
Integer:forBy 0x1163cef38
arg this = 0
arg endval = 0
arg stepval = 2
arg function =
var i = 0
var j = 0
SequenceableCollection:pairsDo 0x116e06968
arg this = [*2]
arg function =
Scheduler:seconds_ 0x116e07818
arg this =
arg newSeconds = 1.252734415
Meta_AppClock:tick 0x1176e20b8
arg this =
var saveClock =
Process:tick 0x1176ef698
arg this =
^^ The preceding error dump is for ERROR: Message 'isPathSeparator' not understood.
RECEIVER: nil

Steps to reproduce:

1. Download sc 3.7 prerelease build
2. Start SC app from within the built folder

Actual result:

Expected result: