I have just imported a VAR layer and edited the conflicts in AX2012 R2 CU7 and AXBuild.exe will no longer run a full compile on the code.  I believe the code should fully compile, but I will verify that with an AOT compile.  AXBuild was successful before the VAR AOD Import step of the checklist.  The code has been synchronized.
Once AXBuild is started, the program will fully complete Pass 1 with three workers. When pass 2 tasks should be starting, 2 of the workers shut down, showing Leg Failed!, Worker completed with result 'Error 100: unknown failure reason'.  The third worker will complete and then the errors begin.  
Error message decoding failed for the error message: #\classes\....names a custom class, list code 12 (a TODO notation in the code)
unhandled Exception: System.AggregateException: One or More Errors occurred.....details are listed below.  I have looked into the temp directory, for the node list file, the error file and the log file for each worker.  All node lists are there, so the folder can be written to correctly, but for the failed workers the error file and log files are missing, which I think explains the file not found part of the error below.
If anyone has ideas I look forward to hearing them.
error details:
System.IO.FileNotFoundException: Could not find file 'C:\Users\ljjohnson\AppDa
ta\Local\Temp\tmpF718_err.tmp'.
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, I
nt32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions o
ptions, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolea
n useLongPath, Boolean checkHost)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access,
FileShare share, Int32 bufferSize, FileOptions options, String msgPath, Boolean
bFromProxy, Boolean useLongPath, Boolean checkHost)
   at System.IO.StreamReader..ctor(String path, Encoding encoding, Boolean detec
tEncodingFromByteOrderMarks, Int32 bufferSize, Boolean checkHost)
   at System.IO.StreamReader..ctor(String path, Encoding encoding, Boolean detec
tEncodingFromByteOrderMarks, Int32 bufferSize)
   at System.IO.StreamReader..ctor(String path, Encoding encoding)
   at System.IO.File.InternalReadAllLines(String path, Encoding encoding)
   at axbuild.Program.UpdateLog(String logFile)
   at axbuild.Program.<>c__DisplayClass4.<Compile_Full>b__3(List`1 nodes)
   at System.Threading.Tasks.Parallel.<>c__DisplayClassf`1.<ForWorker>b__c()
   at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask)
   at System.Threading.Tasks.Task.<>c__DisplayClass10.<ExecuteSelfReplicating>b_
_f(Object param0)
   --- End of inner exception stack trace ---