Use bash in src/test/test-network.sh

This ensures we reliably call chutney's newer tools/test-network.sh when
available.

Fixes bug 21562; bugfix on tor-0.2.9.1-alpha.

changes/bug21562

@@ -0,0 +1,4 @@
+  o Minor bugfixes (testing):
+    - Use bash in src/test/test-network.sh. This ensures we reliably call
+      chutney's newer tools/test-network.sh when available.
+      Fixes bug 21562; bugfix on tor-0.2.9.1-alpha.

src/test/test-network.sh

@@ -1,4 +1,4 @@
-#! /bin/sh
+#! /bin/bash
 
 # Please do not modify this script, it has been moved to chutney/tools
 
@@ -178,7 +178,8 @@ export CHUTNEY_NETWORK=networks/$NETWORK_FLAVOUR
 # And finish up if we're doing a dry run
 if [ "$NETWORK_DRY_RUN" = true ]; then
     # we can't exit here, it breaks argument processing
-    return
+    # this only works in bash: return semantics are shell-specific
+    return 2>/dev/null || exit
 fi
 
 cd "$CHUTNEY_PATH"