Empty ./share/timezone/UTC and failure to set UTC as timezone

Hello,

we are using "embedded" PostgreSQL for integration tests (see
https://github.com/yandex-qatools/postgresql-embedded) and we have noticed
that our (java) clients fail to connect when their timezone is UTC, with PG
server giving following error message:

invalid value for parameter "TimeZone": "UTC"

To double check, I took official 9.6.7 sources, compiled and installed it
locally (/tmp/pgsql) and tried connecting with client again and I again we
got same error message.

When using psql, the same happens:

postgres=# set timezone='UTC';
ERROR: invalid value for parameter "TimeZone": "UTC"

In order to further investigate this, I have attached strace on backend and
I have noticed that PG is able to find and read file ./share/timezone/UTC.
But right after reading the file, we get error message from above.

We noticed that UTC file is empty! Is this on purpose or is this is bug? Am
I missing something?

Kind Regards,

Sasa Vilic