fix: support updating to compatible layout in ``/srv/charm-store``

Last ``compose`` will require ``/srv/charm-store`` not to use symbolic links
because of bad support in windows support.

Signed-off-by: Valentin Lab <valentin.lab@kalysto.org>

precise/host/hooks/install.d/70-0k.sh

@@ -90,10 +90,19 @@ fi
         git clone $GIT_0K_CLONE_OPTIONS "$GIT_0K_BASE/0k/0k-charms.git"
     fi
 
-    if ! [ -d "/srv/charm-store" ]; then
-        mkdir -p /srv/charm-store
+    if [ -d "/srv/charm-store" ]; then
+        if [ -L "/srv/charm-store" ]; then
+            info "Already have a valid /srv/charm-store"
+        elif [ -L "/srv/charm-store/0k-charms" ]; then
+            mv /srv/charm-store{,.old} &&
+                mv /srv/charm-store.old/0k-charms /srv/charm-store &&
+                rmdir /srv/charm-store.old
+        else
+            die "Unexpected layout of '/srv/charm-store'. Bailing out."
+        fi
+    else
+        ln -sfn /opt/apps/0k-charms /srv/charm-store
     fi
-    ln -sfn /opt/apps/0k-charms /srv/charm-store/0k-charms
 
 )