Print the exception origin by fake futures

Fixes #208

concert/async.py

@@ -14,6 +14,7 @@
 
 """
 import functools
+import traceback
 import concert.config
 from concurrent.futures import ThreadPoolExecutor, Future
 
@@ -23,6 +24,14 @@
     import queue
 
 
+# Provide nicely formatted exceptions if possible
+_colored_exceptions = True
+try:
+    from IPython.core.ultratb import AutoFormattedTB
+except ImportError:
+    _colored_exceptions = False
+
+
 # Patch futures so that they provide a join() and kill() method
 def _join(self, _timeout=None):
     self.result()
@@ -52,6 +61,10 @@ def _inner(*args, **kwargs):
             result = func(*args, **kwargs)
             future.set_result(result)
         except Exception as e:
+            if _colored_exceptions:
+                AutoFormattedTB(mode='Verbose')()
+            else:
+                traceback.print_exc()
             future.set_exception(e)
 
         return future