Multi-config Xcode builds for application bundles result in exception

[markfinal]

ERROR: (Bam.Core.Exception) Error during non-threaded build
ERROR: (Bam.Core.Exception) Product type has already been set to ApplicationBundle. Cannot change it
ERROR:
at XcodeBuilder.Target.SetProductType (EProductType type) [0x0003b] in /Users/mark/dev/BuildAMation/packages/XcodeBuilder/bam/Scripts/Target.cs:135
at XcodeBuilder.Target.EnsureOutputFileReferenceExists (Bam.Core.TokenizedString path, EFileType type, EProductType productType) [0x00003] in /Users/mark/dev/BuildAMation/packages/XcodeBuilder/bam/Scripts/Target.cs:161
at C.XcodeLinker.C.ILinkingPolicy.Link (C.ConsoleApplication sender, Bam.Core.ExecutionContext context, Bam.Core.TokenizedString executablePath, System.Collections.ObjectModel.ReadOnlyCollection1 objectFiles, System.Collections.ObjectModel.ReadOnlyCollection1 headers, System.Collections.ObjectModel.ReadOnlyCollection1 libraries, System.Collections.ObjectModel.ReadOnlyCollection1 frameworks) [0x00065] in /Users/mark/dev/BuildAMation/packages/C/bam/XcodeBuilder/XcodeLinker.cs:52
at C.ConsoleApplication.ExecuteInternal (Bam.Core.ExecutionContext context) [0x0005e] in /Users/mark/dev/BuildAMation/packages/C/bam/Scripts/ConsoleApplication.cs:235
at Bam.Core.Module.Bam.Core.IModuleExecution.Execute (Bam.Core.ExecutionContext context) <0x37c8950 + 0x00143> in :0
at Bam.Core.Executor+c__AnonStorey2.<>m__0 () <0x37c80f0 + 0x00266> in :0

[markfinal]

This was actually a fix for issue #65.

[markfinal]

This exception only happens when there are modules that are configuration specific. e.g. only build an installer in non-debug builds. This causes the modules for each configuration to be in a skewed order, which may result in collation policies (which change the product type) to be executed before the link step for the same executable (in the eyes of Xcode) in another configuration. Thus the product type goes from NA->Executable->Application Bundle(first config)->Executable(second config) and that's the issue.