>>> cfg-update-1.8.2-r1: Skipping checksum index updating...
 * Using: sun-jdk-1.6
>>> Unpacking source...
>>> Unpacking josm-1566.tar.lzma to /var/tmp/portage/sci-geosciences/josm-1.566/work
>>> Source unpacked in /var/tmp/portage/sci-geosciences/josm-1.566/work
>>> Compiling source in /var/tmp/portage/sci-geosciences/josm-1.566/work/josm ...
cElementTree rewriter
 * Disabling all optional ANT_TASKS
Buildfile: build.xml

init:
    [mkdir] Created dir: /var/tmp/portage/sci-geosciences/josm-1.566/work/josm/build
    [mkdir] Created dir: /var/tmp/portage/sci-geosciences/josm-1.566/work/josm/dist

compile:
    [javac] Compiling 308 source files to /var/tmp/portage/sci-geosciences/josm-1.566/work/josm/build
    [javac] /var/tmp/portage/sci-geosciences/josm-1.566/work/josm/src/org/openstreetmap/josm/io/MyHttpHandler.java:10: warning: sun.net.www.protocol.http.Handler is Sun proprietary API and may be removed in a future release
    [javac] public class MyHttpHandler extends sun.net.www.protocol.http.Handler  {
    [javac]                                                             ^
    [javac] /var/tmp/portage/sci-geosciences/josm-1.566/work/josm/src/org/openstreetmap/josm/io/MyHttpURLConnection.java:8: warning: sun.net.www.protocol.http.HttpURLConnection is Sun proprietary API and may be removed in a future release
    [javac] public class MyHttpURLConnection extends sun.net.www.protocol.http.HttpURLConnection {
    [javac]                                                                   ^
    [javac] /var/tmp/portage/sci-geosciences/josm-1.566/work/josm/src/org/openstreetmap/josm/io/MyHttpURLConnection.java:9: warning: sun.net.www.protocol.http.Handler is Sun proprietary API and may be removed in a future release
    [javac]             protected MyHttpURLConnection(URL u, Proxy p, sun.net.www.protocol.http.Handler handler)
    [javac]                                                                                    ^
    [javac] Note: Some input files use unchecked or unsafe operations.
    [javac] Note: Recompile with -Xlint:unchecked for details.
    [javac] 3 warnings

dist:
    [unjar] Expanding: /var/tmp/portage/sci-geosciences/josm-1.566/work/josm/lib/gettext-commons-0.9.2.jar into /var/tmp/portage/sci-geosciences/josm-1.566/work/josm/build
    [unjar] Expanding: /var/tmp/portage/sci-geosciences/josm-1.566/work/josm/lib/metadata-extractor-2.3.1-nosun.jar into /var/tmp/portage/sci-geosciences/josm-1.566/work/josm/build
    [unjar] Expanding: /var/tmp/portage/sci-geosciences/josm-1.566/work/josm/lib/josm-translation.jar into /var/tmp/portage/sci-geosciences/josm-1.566/work/josm/build
     [exec] Result: 127
[xmlproperty] [Fatal Error] REVISION:1:1: Content is not allowed in prolog.

BUILD FAILED
/var/tmp/portage/sci-geosciences/josm-1.566/work/josm/build.xml:35: Failed to load /var/tmp/portage/sci-geosciences/josm-1.566/work/josm/REVISION

Total time: 5 seconds
 * 
 * ERROR: sci-geosciences/josm-1.566 failed.
 * Call stack:
 *               ebuild.sh, line   48:  Called src_compile
 *             environment, line 4093:  Called eant 'dist'
 *             environment, line  913:  Called die
 * The specific snippet of code:
 *       ant ${antflags} "${@}" || die "eant failed"
 *  The die message:
 *   eant failed
 * 
 * If you need support, post the topmost build error, and the call stack if relevant.
 * A complete build log is located at '/var/tmp/portage/sci-geosciences/josm-1.566/temp/build.log'.
 * The ebuild environment file is located at '/var/tmp/portage/sci-geosciences/josm-1.566/temp/environment'.
 * 
!!! When you file a bug report, please include the following information:
GENTOO_VM=sun-jdk-1.6  CLASSPATH="" JAVA_HOME="/opt/sun-jdk-1.6.0.13"
JAVACFLAGS="-source 1.6 -target 1.6" COMPILER="javac"
and of course, the output of emerge --info