flexi_splitter: double escape sed cmd

src/nf_modules/flexi_splitter/main.nf

@@ -58,7 +58,7 @@ process split_file {
   rm -Rf split/unassigned
   mkdir -p results/
   find split -type "f" | \
-    sed -E "s|(.*/split/(.*)/(.*))|\1 \2_\3|g" |
+    sed -E "s|(.*/split/(.*)/(.*))|\\1 \\2_\\3|g" |
     awk '{system("mv "\$1" results/"\$2)}'
   """
 }