launch the pager process in its own process group so that it isn't killed with ctrl+c

jsvn

@@ -1387,7 +1387,8 @@ def do_cmd(argv, realsvn, config, expand=True):
                 pager = os.environ['PAGER']
             else:
                 pager = 'less -FRX'
-            pager_proc = Popen(pager, shell=True, stdin=PIPE)
+            pager_proc = Popen(pager, shell=True, stdin=PIPE,
+                    preexec_fn=os.setsid)
             out = pager_proc.stdin
             using_pager = True