Fix fallback logic in run-os-net-config.sh

The expression "${variable:-''}" with $variable unset results in a
value that looks like "''", which will not pass a -z test, as I
believe is intended in this code.  Making the default value blank
yields the correct behavior.

Change-Id: I9fe98f3c69c797feb9c37da1ad8c7912a15bcecb
Closes-Bug: 1699614

diff --git a/network/scripts/run-os-net-config.sh b/network/scripts/run-os-net-config.sh
index 8fe2d27..864da24 100755 (executable)
--- a/network/scripts/run-os-net-config.sh
+++ b/network/scripts/run-os-net-config.sh
@@ -110,7 +110,7 @@ EOF_CAT
 }
 
 if [ -n '$network_config' ]; then
-    if [ -z "${disable_configure_safe_defaults:-''}" ]; then
+    if [ -z "${disable_configure_safe_defaults:-}" ]; then
         trap configure_safe_defaults EXIT
     fi