Fix ephemeral layer addition

usr/lib/python3.8/spoc/container.py

@@ -75,6 +75,9 @@ class Container:
         # Prepares container rootfs
         # Called in lxc.hook.pre-start as the standard mount options are insufficient for rootless containers (see notes for overlayfs below)
         layers = [os.path.join(LAYERS_DIR, layer) for layer in self.layers]
+        if not self.build:
+            # Add ephemeral layer if the container is not created as part of build process
+            layers.append(self.ephemeral_layer_path)
         if len(layers) > 1:
             # Multiple layers require overlayfs, however non-root users don't normally have capability to create overlayfs mounts - https://www.spinics.net/lists/linux-fsdevel/msg105877.html
             # Standard linux kernels currently doesn't support overlay mounts in user namespaces (lxc.hook.pre-mount)
@@ -110,11 +113,6 @@ class Container:
         # Chown is possible only when the process is running as root, for user namespaces, see https://linuxcontainers.org/lxc/manpages/man1/lxc-usernsexec.1.html
         os.chown(self.ephemeral_layer_path, 100000, 100000)
         # Create container configuration file based on the container definition
-        layers = [os.path.join(LAYERS_DIR, layer) for layer in self.layers]
-        if not self.build:
-            # Add ephemeral layer if the container is not created as part of build process
-            layers.append(self.ephemeral_layer_path)
-        layers = ','.join(layers)
         mounts = '\n'.join([f'lxc.mount.entry = {os.path.join(VOLUME_DIR, v)} {m[0]} none bind,create={"dir" if m[1] else "file"} 0 0' for v,m in self.mounts.items()])
         env = '\n'.join([f'lxc.environment = {k}={v}' for k,v in self.env.items()])
         uid = self.uid if self.uid else 0