Mercurial: error indexing content of file with unicode name on Windows

hg cat command is executed during content indexing with filename passed as an argument and while Windows converts arguments to ANSI codepage, garbled filename gets to git process, eg:

> hg --config ui.verbose=false cat -r 547a7f4d4890c363836ebe7ae0bfb7e2dc421095 αφιλε.τχτ
?????.???: no such file in rev 547a7f4d4890

This leads to an error during indexing file content being printed to log and visible in Administration > Repository Status > Recent Errors section:

Problem indexing content of "αφιλε.τχτ" for rev "547a7f4d4890c363836ebe7ae0bfb7e2dc421095" from repo "unicode-file-names" due to class com.atlassian.fisheye.dvcs.handler.DvcsProcessException - Error while communicating with VCS: ???.?: no such file in rev 547a7f4d4890

and also an attempt to display file content (request for /browse/unicode-file-names/%CE%B1%CF%86%CE%B9%CE%BB%CE%B5.%CF%84%CF%87%CF%84?r=547a7f4d4890c363836ebe7ae0bfb7e2dc421095) cause an error to be displayed.

Described problem occurs if file.encoding is set to UTF-8 (it's a value that we recommend user to force during fisheye startup). When run with default windows encoding (windows-1250) there are no indexing errors, file content can be displayed, but filename gets garbled:

αφιλε.τχτ