themes: don't reset theme on package upgrades

Fixes: #2743
Signed-off-by: Jo-Philipp Wich <jo@mein.io>

themes/luci-theme-bootstrap/root/etc/uci-defaults/30_luci-theme-bootstrap

@@ -1,7 +1,11 @@
 #!/bin/sh
-uci batch <<-EOF
+
+if [ "$PKG_UPGRADE" != 1 ]; then
+	uci batch <<-EOF
 		set luci.themes.Bootstrap=/luci-static/bootstrap
 		set luci.main.mediaurlbase=/luci-static/bootstrap
 		commit luci
-EOF
+	EOF
+fi
+
 exit 0

themes/luci-theme-material/root/etc/uci-defaults/30_luci-theme-material

@@ -1,7 +1,11 @@
 #!/bin/sh
-uci batch <<-EOF
+
+if [ "$PKG_UPGRADE" != 1 ]; then
+	uci batch <<-EOF
 		set luci.themes.Material=/luci-static/material
 		set luci.main.mediaurlbase=/luci-static/material
 		commit luci
-EOF
+	EOF
+fi
+
 exit 0

themes/luci-theme-openwrt/root/etc/uci-defaults/30_luci-theme-openwrt

@@ -1,6 +1,11 @@
 #!/bin/sh
-uci batch <<-EOF
+
+if [ "$PKG_UPGRADE" != 1 ]; then
+	uci batch <<-EOF
 		set luci.themes.OpenWrt=/luci-static/openwrt.org
 		set luci.main.mediaurlbase=/luci-static/openwrt.org
 		commit luci
-EOF
+	EOF
+fi
+
+exit 0

themes/luci-theme-rosy/root/etc/uci-defaults/30_luci-theme-rosy

@@ -1,7 +1,11 @@
 #!/bin/sh
-uci batch <<-EOF
+
+if [ "$PKG_UPGRADE" != 1 ]; then
+	uci batch <<-EOF
 		set luci.themes.Rosy=/luci-static/rosy
 		set luci.main.mediaurlbase=/luci-static/rosy
 		commit luci
-EOF
+	EOF
+fi
+
 exit 0