shellcheck: fix warnings in the bootstrap-network.sh script

Part of 30065.

tools/bootstrap-network.sh

@@ -14,12 +14,13 @@
 #
 
 # Get a working chutney path
-if [ ! -d "$CHUTNEY_PATH" -o ! -x "$CHUTNEY_PATH/chutney" ]; then
+if [ ! -d "$CHUTNEY_PATH" ] || [ ! -x "$CHUTNEY_PATH/chutney" ]; then
     # looks like a broken path: use the path to this tool instead
-    TOOLS_PATH=`dirname "$0"`
-    export CHUTNEY_PATH=`dirname "$TOOLS_PATH"`
+    TOOLS_PATH=$(dirname "$0")
+    CHUTNEY_PATH=$(dirname "$TOOLS_PATH")
+    export CHUTNEY_PATH
 fi
-if [ -d "$PWD/$CHUTNEY_PATH" -a -x "$PWD/$CHUTNEY_PATH/chutney" ]; then
+if [ -d "$PWD/$CHUTNEY_PATH" ] && [ -x "$PWD/$CHUTNEY_PATH/chutney" ]; then
     # looks like a relative path: make chutney path absolute
     export CHUTNEY_PATH="$PWD/$CHUTNEY_PATH"
 fi