format tracebacks with cause

This reverts commit 84e00eb.

Author: Alex Boten

lightstep/recorder.py

@@ -14,7 +14,7 @@
 import warnings
 
 from basictracer.recorder import SpanRecorder
-from opentracing.logs import ERROR_KIND, STACK
+from opentracing.logs import ERROR_KIND, STACK, ERROR_OBJECT
 
 from lightstep.http_converter import HttpConverter
 from lightstep.thrift_converter import ThriftConverter
@@ -171,7 +171,11 @@ def _normalize_log(self, log):
                 log.key_values[ERROR_KIND] = util._format_exc_type(log.key_values[ERROR_KIND])
 
             if STACK in log.key_values:
-                log.key_values[STACK] = util._format_exc_tb(log.key_values[STACK])
+                log.key_values[STACK] = util._format_exc_tb(
+                    log.key_values.get(ERROR_OBJECT),
+                    log.key_values.get(ERROR_KIND),
+                    log.key_values[STACK]
+                )
 
         return log
 

lightstep/util.py

@@ -105,9 +105,9 @@ def _coerce_to_unicode(val):
             return '(encoding error)'
 
 
-def _format_exc_tb(exc_tb):
+def _format_exc_tb(exc_value, exc_type, exc_tb):
     if type(exc_tb) is types.TracebackType:
-        return ''.join(traceback.format_tb(exc_tb))
+        return ''.join(traceback.format_exception(exc_value, exc_type, exc_tb))
 
     return exc_tb