RAT runs very slowly on some input

Commons IO discovered that mvn site was spending a lot of time running RAT 0.9. Reverting to 0.8 fixes the problem.
Turns out that certain files seem to cause RAT to chew CPU in the Pattern.matcher; here is a sample stack trace from a thread dump:

"main" prio=6 tid=0x003c8c00 nid=0xa4c runnable [0x00a5e000]
java.lang.Thread.State: RUNNABLE
at java.util.regex.Pattern$Curly.match0(Pattern.java:4166)
at java.util.regex.Pattern$Curly.match(Pattern.java:4132)
at java.util.regex.Matcher.match(Matcher.java:1221)
at java.util.regex.Matcher.matches(Matcher.java:559)
at org.apache.rat.analysis.license.FullTextMatchingLicense.match(FullTextMatchingLicense.java:79)
at org.apache.rat.analysis.util.HeaderMatcherMultiplexer.match(HeaderMatcherMultiplexer.java:42)
at org.apache.rat.analysis.HeaderCheckWorker.readLine(HeaderCheckWorker.java:113)
at org.apache.rat.analysis.HeaderCheckWorker.read(HeaderCheckWorker.java:84)
at org.apache.rat.analysis.DocumentHeaderAnalyser.analyse(DocumentHeaderAnalyser.java:43)
at org.apache.rat.analysis.DefaultAnalyserFactory$DefaultAnalyser.analyse(DefaultAnalyserFactory.java:60)
at org.apache.rat.document.impl.util.DocumentAnalyserMultiplexer.analyse(DocumentAnalyserMultiplexer.java:37)
at org.apache.rat.report.claim.util.ClaimReporterMultiplexer.report(ClaimReporterMultiplexer.java:42)
at org.apache.rat.mp.FilesReportable.run(FilesReportable.java:68)
at org.apache.rat.Report.report(Report.java:393)
at org.apache.rat.Report.report(Report.java:373)
at org.apache.rat.mp.AbstractRatMojo.createReport(AbstractRatMojo.java:462)
at org.apache.rat.mp.RatReportMojo.createReport(RatReportMojo.java:148)
at org.apache.rat.mp.RatReportMojo.generate(RatReportMojo.java:310)
at org.apache.rat.mp.RatReportMojo.execute(RatReportMojo.java:210)

I assume there must be a problem with one of the REs which is triggering lots of backtracking when applied to files under site-content/, which is a working copy of:

https://svn.apache.org/repos/infra/websites/production/commons/content/proper/commons-io
Last Changed Rev: 861378

This directory should not have been included in the RAT scan, but the files don't cause problems for RAT 0.8.