Fix exception on transmission abort with python3

With python3 sys.exc_value does no longer exist, but we can replace it
with sys.exc_info().

ChangeLog

@@ -2,6 +2,12 @@ servefile changelog
 ===================
 
 
+Unreleased
+----------
+
+	* fixed bug where exception was shown on transmission abort with python3
+
+
 2020-10-30 v0.5.1
 -----------------
 

servefile/servefile.py

@@ -714,7 +714,8 @@ class FilePutter(BaseHTTPServer.BaseHTTPRequestHandler):
 
 class ThreadedHTTPServer(SocketServer.ThreadingMixIn, BaseHTTPServer.HTTPServer):
 	def handle_error(self, request, client_address):
-		print("%s ABORTED transmission (Reason: %s)" % (client_address[0], sys.exc_value))
+		_, exc_value, _ = sys.exc_info()
+		print("%s ABORTED transmission (Reason: %s)" % (client_address[0], exc_value))
 
 
 def catchSSLErrors(BaseSSLClass):

tests/test_servefile.py

@@ -356,3 +356,24 @@ def test_https_big_download(run_servefile, datadir):
 
     urllib3.disable_warnings()
     check_download(data, protocol='https', verify=False)
+
+
+def test_abort_download(run_servefile, datadir):
+    data = "x" * (10 * 1024 ** 2)
+    p = datadir({'testfile': data}) / 'testfile'
+    env = os.environ.copy()
+    env['PYTHONUNBUFFERED'] = '1'
+    proc = run_servefile(str(p), stdout=subprocess.PIPE, stderr=subprocess.STDOUT, env=env)
+
+    # provoke a connection abort
+    # hopefully the buffers will not fill up with all of the 10mb
+    sock = socket.socket(socket.AF_INET)
+    sock.connect(("localhost", 8080))
+    sock.send(b"GET /testfile HTTP/1.0\n\n")
+    resp = sock.recv(100)
+    assert resp != b''
+    sock.close()
+    time.sleep(0.1)
+    proc.kill()
+    out = proc.stdout.read().decode()
+    assert "127.0.0.1 ABORTED transmission" in out