always apk upgrade builder VM, fix --clean of symlinked dirs

Fix for softlinks to directories during --clean / always use latest packages within a release at build time to pick up latest security fixes etc.

build

@@ -95,7 +95,7 @@ def clean_work():
     for x in (set(os.listdir('work')) - WORK_CLEAN):
         x = os.path.join('work', x)
         log.debug('removing %s', x)
-        if os.path.isdir(x):
+        if os.path.isdir(x) and not os.path.islink(x):
             shutil.rmtree(x)
         else:
             os.unlink(x)

scripts/setup

@@ -22,6 +22,8 @@ setup_builder() {
     einfo "Setting up Builder Instance"
     setup-apkrepos -1   # main repo via dl-cdn
     # ODO? also uncomment community repo?
+    # Always use latest versions within the release, security patches etc.
+    apk upgrade --no-cache --available
     apk --no-cache add \
         e2fsprogs \
         dosfstools \