stream: Fix exception traceback handling

sys.exc_info() returns a 3-tuple (type, value, traceback). Raising just
`value` again looses the traceback information as this creates a new
exception.

Just use `raise` which re-raises the previous exception including the
original traceback.

FYI: There is a subtile difference between Python 2 and Python 3:

> try:
>     raise ValueError()
> except ValueError:
>     try:
>         raise TypeError()
>     except TypeError:
>         pass
>     raise

With Python 3 the exception environment is dropped after the exception
has been handled - as such Python 3 re-raises the outer ValueError.

With Python 2 the last (inner) exception is raised: TypeError

Signed-off-by: Philipp Hahn <hahn@univention.de>

1 files changed, 2 insertions, 4 deletions

diff --git a/libvirt-override-virStream.py b/libvirt-override-virStream.py
index 998ad41..2d716eb 100644
--- a/libvirt-override-virStream.py
+++ b/libvirt-override-virStream.py
@@ -52,12 +52,11 @@
                 if type(ret) is int and ret < 0:
                     raise RuntimeError("recvAll handler returned %d" % ret)
             except BaseException:
-                e = sys.exc_info()[1]
                 try:
                     self.abort()
                 except Exception:
                     pass
-                raise e
+                raise
 
     def sendAll(self, handler: Callable[['virStream', int, _T], bytes], opaque: _T) -> None:
         """
@@ -77,12 +76,11 @@
             try:
                 got = handler(self, virStorageVol.streamBufSize, opaque)
             except BaseException:
-                e = sys.exc_info()[1]
                 try:
                     self.abort()
                 except Exception:
                     pass
-                raise e
+                raise
 
             if not got:
                 break