Backend: work around ongoing TWRP SAR support fragmentation

TWRP now has 3(!) different competing implementations of SAR currently in use by maintainers:
1) /system as mountpoint in ramdisk/fstab and ANDROID_ROOT=/system, and possible symlink from /system_root to /system
2) /system_root as mountpoint in ramdisk/fstab, ANDROID_ROOT=/system_root, and possible symlink from /system to /system_root/system
3) /system_root as mountpoint in ramdisk/fstab, ANDROID_ROOT=/system, and possible symlink from /system to /system_root/system

Attempt to continue to accommodate this bullshit.

1 files changed, 5 insertions, 2 deletions

diff --git a/META-INF/com/google/android/update-binary b/META-INF/com/google/android/update-binary
index 4e9b5cb..34dfc6c 100755
--- a/META-INF/com/google/android/update-binary
+++ b/META-INF/com/google/android/update-binary
@@ -86,12 +86,15 @@ umount_apex() {
 mount_all() {
   setup_mountpoint $ANDROID_ROOT;
   if ! is_mounted $ANDROID_ROOT; then
-    $BB mount -o ro -t auto $ANDROID_ROOT;
+    $BB mount -o ro -t auto $ANDROID_ROOT 2>/dev/null;
   fi;
   case $ANDROID_ROOT in
     /system_root) setup_mountpoint /system;;
     /system)
-      if [ -f /system/system/build.prop ]; then
+      if ! is_mounted /system && ! is_mounted /system_root; then
+        setup_mountpoint /system_root;
+        $BB mount -o ro -t auto /system_root;
+      elif [ -f /system/system/build.prop ]; then
         setup_mountpoint /system_root;
         $BB mount --move /system /system_root;
         if [ $? != 0 ]; then