Error with outputEncoding parameter set to UTF-8

When using UTF-8 as setting for the parameter outputEncoding, we've got this error:

[INFO] Generating "Change Log" report.
[INFO] Generating changed sets xml to: D:\devs\projects\Test\workspace\TestWebapp\target\changelog.xml
[INFO] Executing: svn --non-interactive log -v -r "

:

" https://mysubversionsrv/svndev/test/trunk/TestWebapp
[INFO] Working directory: D:\devs\projects\Test\workspace\TestWebapp
[INFO] Generating "Developer Activity" report.
[INFO] Using existing changelog.xml...
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Error during page generation

Embedded error: Error rendering Maven report: An error occurred while parsing D:
\devs\projects\Test\workspace\TestWebapp\target\changelog.xml
Invalid byte 1 of 1-byte UTF-8 sequence.
[INFO] ------------------------------------------------------------------------
[INFO] For more information, run Maven with the -e switch
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 39 seconds
[INFO] Finished at: Wed Jun 04 13:45:23 CEST 2008
[INFO] Final Memory: 41M/63M
[INFO] ------------------------------------------------------------------------

The file changelog.xml contains the good header line (<?xml version="1.0" encoding="UTF-8"?>), but the file is encoded with ANSI UNIX charset