If the release plugin has run but the release failed, it leaves your POMs
modified with the new version numbers. If your SCM uses update this will mean
that subsequent builds (or releases) will see the modified version numbers.

Apart from logging in and manually doing "svn revert", or just removing the
workspace entirely, there is no easy way for a user to fix this after a failed
release.

Possibly this problem is related to the enhancement 3925.