Debug flag to not intercept pipeline exceptions

Cython/Compiler/DebugFlags.py

@@ -8,3 +8,6 @@ debug_temp_code_comments = 0
 
 # Write a call trace of the code generation phase into the C code
 debug_trace_code_generation = 0
+
+# Do not replace exceptions with user-friendly error messages
+debug_no_exception_intercept = 0

Cython/Compiler/Visitor.py

@@ -7,6 +7,7 @@ import Nodes
 import ExprNodes
 import Naming
 import Errors
+import DebugFlags
 from StringEncoding import EncodedString
 
 class BasicVisitor(object):
@@ -151,6 +152,8 @@ class TreeVisitor(BasicVisitor):
             raise
         except Exception, e:
             import sys
+            if DebugFlags.debug_no_exception_intercept:
+                raise
             trace = ['']
             for parent, attribute, index in self.access_path:
                 node = getattr(parent, attribute)