Invalid encoding of process output

Hello,
While trying to perform backup with Russian-speaking PostgreSQL 10 (on Linux) I get the following unreadable messages:



This bug is caused by the ansi encoding chosen when reading the process log file.
Please look at the proposed fix. (It corresponds to all the other sys.getdefaultencoding() calls in the code.)

Best regards,
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Alexander Lakhin
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company