Retry to update Unicode timestamp

.travis.yml

@@ -420,8 +420,12 @@ before_script:
   - "> config.status"
   - "> .rbconfig.time"
   - sed -f tool/prereq.status template/Makefile.in common.mk > Makefile
-  - date; make touch-unicode-files
-  - date; make --debug -s $JOBS $UPDATE_UNICODE up
+  - |-
+    for i in 1 2 3; do
+      date; make touch-unicode-files || break
+      ls -l tool/generic_erb.rb template/unicode_norm_gen.tmpl enc/unicode/data/*/ucd/.unicode-tables.time
+      date; make -s $JOBS $UPDATE_UNICODE up && break
+    done
   - date; make -s $JOBS srcs
   - rm -f config.status Makefile rbconfig.rb .rbconfig.time
   - |-