Add epoch.rake

Author: nobu

rakelib/epoch.rake

@@ -0,0 +1,5 @@
+task "build" => "date_epoch"
+
+task "date_epoch" do
+  ENV["SOURCE_DATE_EPOCH"] = IO.popen(%W[git -C #{__dir__} log -1 --format=%ct], &:read).chomp
+end