root@3287454ea40e98:/app# cat releases/COOKIE
NLJUCOSN4EAOYXBAXMAIHATUPVFYGNC7CXFK25BWYRKUMJCXM2VA====root@3287454ea40e98:/app#
Looks like there is no \n at the end of the file. The contents are NLJUCOSN4EAOYXBAXMAIHATUPVFYGNC7CXFK25BWYRKUMJCXM2VA====
You can double check by running
cat releases/COOKIE; echo
instead.
Thanks