I could not find any build (including my own builds) that knew what build they were. Sample:

mike@samuel:~/code/jdk/tl8$ ~/jdk-tools/jtreg/win32/bin/jtdiff -version
(unknown), version (unknown) (unknown) (unknown)
Installed in /home/mike/jdk-tools/jtreg-4.1-b07-nightly/lib/jtreg.jar
Running on platform version 1.7.0_25 from /usr/lib/jvm/java-7-openjdk-amd64/jre.
Built with (unknown) on (unknown).
Copyright (c) 2008 Oracle and/or its affiliates. All rights reserved.
Use is subject to license terms.

and the copy from /java/re/jtreg:

-bash-3.00$ /java/re/jtreg/4.1/promoted/fcs/b07/binaries/jtreg/win32/bin/jtdiff -version
(unknown), version (unknown) (unknown) (unknown)
Installed in /net/jre.us.oracle.com/p/v10/jtreg/4.1/fcs/b07/binaries/jtreg/lib/jtreg.jar
Running on platform version 1.6.0_22 from /usr/jdk/instances/jdk1.6.0/jre.
Built with (unknown) on (unknown).
Copyright (c) 2008 Oracle and/or its affiliates. All rights reserved.
Use is subject to license terms.