email-ext fails with a NullPointerException when sending some emails (not all).

I am not a java developer but if someone could send me a version of email-ext having this line (ContentBuilder.java:68) devided in several lines, next time it fails we could locate more precisely the error.

Here is the stack I have:
----------------------------------------------
Build step 'Execute shell' marked build as failure
Email was triggered for: Failure
Sending email for trigger: Failure
ERROR: Could not send email as a part of the post-build publishers.
java.lang.NullPointerException
at java.util.regex.Matcher.quoteReplacement(Matcher.java:598)
at hudson.plugins.emailext.plugins.ContentBuilder.transformText(ContentBuilder.java:68)
at hudson.plugins.emailext.ExtendedEmailPublisher.setSubject(ExtendedEmailPublisher.java:463)
at hudson.plugins.emailext.ExtendedEmailPublisher.createMail(ExtendedEmailPublisher.java:311)
at hudson.plugins.emailext.ExtendedEmailPublisher.sendMail(ExtendedEmailPublisher.java:259)
at hudson.plugins.emailext.ExtendedEmailPublisher._perform(ExtendedEmailPublisher.java:251)
at hudson.plugins.emailext.ExtendedEmailPublisher.perform(ExtendedEmailPublisher.java:211)
at hudson.tasks.BuildStepMonitor$3.perform(BuildStepMonitor.java:36)
at hudson.model.AbstractBuild$AbstractRunner.perform(AbstractBuild.java:703)
at hudson.model.AbstractBuild$AbstractRunner.performAllBuildSteps(AbstractBuild.java:678)
at hudson.model.AbstractBuild$AbstractRunner.performAllBuildSteps(AbstractBuild.java:656)
at hudson.model.Build$RunnerImpl.cleanUp(Build.java:171)
at hudson.model.Run.run(Run.java:1454)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:238)
Finished: FAILURE