Inconsistent ellipsis in regression test error message?

The most recent cfbot run for a patch I am interested in has failed a
newly added regression test.

Please see http://cfbot.cputube.org/ for 36/2906

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The failure logs [2] are very curious because the error message is
what was expected but it has a different position of the ellipsis
(...).

But only for Windows.

-- fail - publication WHERE clause must be boolean
ALTER PUBLICATION testpub5 SET TABLE testpub_rf_tbl3 WHERE (1234);
ERROR: argument of PUBLICATION WHERE must be type boolean, not type integer
-LINE 1: ALTER PUBLICATION testpub5 SET TABLE testpub_rf_tbl3 WHERE (...
+LINE 1: ...PUBLICATION testpub5 SET TABLE testpub_rf_tbl3 WHERE (1234);

How is that possible?

Is this a problem caused by the patch code? If so, how?

Or is this some obscure boundary case bug of the error ellipsis
calculation which I've exposed by accident due to the specific length
of my bad command?

Thanks for any ideas!

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[2] https://ci.appveyor.com/project/postgresql-cfbot/postgresql/build/1.0.157408

Kind Regards,
Peter Smith.
Fujitsu Australia