Print the date to STDERR if STDIN is a part of input [ci skip]

1 files changed, 3 insertions, 2 deletions

diff --git a/tool/update-bundled_gems.rb b/tool/update-bundled_gems.rb
index 2f088804ef..f27ba98961 100755
--- a/tool/update-bundled_gems.rb
+++ b/tool/update-bundled_gems.rb
@@ -2,10 +2,11 @@
 BEGIN {
   require 'rubygems'
   date = nil
-}
-END {
   # STDOUT is not usable in inplace edit mode
   output = $-i ? STDOUT : STDERR
+}
+output = STDERR if ARGF.file == STDIN
+END {
   output.print date.strftime("latest_date=%F") if date
 }
 unless /^[^#]/ !~ (gem = $F[0])