travis: do not keep prepared_image/*.img, to save space

There is limited disk space available on Travis-CI. Build product it
thrown away anyawy, so do not keep intermediate files (normally useful
to speedup next build).

qubeize_image

@@ -61,8 +61,13 @@ trap cleanup ERR
 export IMG="qubeized_images/$NAME/root.img"
 mkdir -p "qubeized_images/$NAME"
 
-echo "--> Copying $CLEANIMG to $IMG..."
-cp "$CLEANIMG" "$IMG" || exit 1
+if [ "$TRAVIS" = "true" ]; then
+    echo "--> Moving $CLEANIMG to $IMG (save space on Travis-CI)..."
+    mv "$CLEANIMG" "$IMG" || exit 1
+else
+    echo "--> Copying $CLEANIMG to $IMG..."
+    cp "$CLEANIMG" "$IMG" || exit 1
+fi
 
 echo "--> Mounting $IMG"
 mkdir -p mnt