Set goal with newVersion and oldVersion arguments specified fails to update only the versions which matches the oldVersion and updates all the versions.

Example :
command line / mvn versions:set -DnewVersion="TEST" -DoldVersion="TEST2"

Sample maven execution output log lines :

[INFO] Processing change of com.some.obscure.company.someniftymodule-parent:TEST2 -> TEST
.
.
.
[INFO] Updating project com.some.obscure.company.someniftymodule-document-parent
[INFO] from version 0.101.1-SNAPSHOT to TEST

Possible Solution :
Please see the diff file in the zip archive below for the possible fix.

oldVersion_fix.zip