Merge pull request #185 from tonistiigi/xx-apk-lock

xx-apk: fix problem with writing lock in latest alpine

Author: tonistiigi

src/xx-apk

@@ -3,11 +3,14 @@
 set -e
 
 if [ -z "$XX_APK_NOLOCK" ]; then
+  # readlink -f in ash can not resolve symlinks from deep workdir
+  cd /
   if [ -L /var/lock ] && [ ! -e "$(readlink -f /var/lock)" ]; then
     mkdir -p "$(readlink -f /var/lock)"
   elif [ ! -d /var/lock ]; then
     mkdir -p /var/lock
   fi
+  cd -
   lock="/var/lock/xx-apk"
   exec 9>$lock
   flock -x 9