test-worker: disable tests of forked workers on Windows stable

test-worker: disable tests of forked workers on Windows

The number of the "Traceback" lines differs on Windows because the main
process does not raise SystemExit.

--- a/tests/test-worker.t	Thu Apr 20 22:45:45 2017 +0900
+++ b/tests/test-worker.t	Thu Apr 20 22:51:28 2017 +0900
@@ -70,6 +70,8 @@
   run
   done
 
+#if no-windows
+
 Known exception should be caught, but printed if --traceback is enabled
 
   $ hg --config "extensions.t=$abspath" --config 'worker.numcpus=2' \
@@ -88,3 +90,5 @@
   $ hg --config "extensions.t=$abspath" --config 'worker.numcpus=2' \
   > test 100000.0 exc 2>&1 | grep '^Traceback'
   Traceback (most recent call last):
+
+#endif