Add support for CVS branch aliases

JIRA fails to parse CVS log files which contain branch aliases (which can be created using 'cvs admin -nbranch_alias_name:branch_name' command). The exception in teh logs looks like:

2005-03-28 13:43:25,214 ERROR [action.admin.vcs.AddRepository] Error occurred while obtaining cvs log or parsing the cvs log.
java.lang.IllegalStateException: Already have branch data: name='xxxx' branchRevision='1.3.0.2' revisonNumber='1.3.2 startRevisionN
umber='1.3'
at net.sf.statcvs.input.CvsRevisionParser.setBranchInformation(CvsRevisionParser.java:200)
at net.sf.statcvs.input.CvsRevisionParser.parseRevision(CvsRevisionParser.java:167)
at net.sf.statcvs.input.CvsRevisionParser.parse(CvsRevisionParser.java:103)
at net.sf.statcvs.input.CvsFileBlockParser.parse(CvsFileBlockParser.java:115)
at net.sf.statcvs.input.CvsLogfileParser.parse(CvsLogfileParser.java:84)
at com.atlassian.jira.vcs.cvsimpl.CvsRepositoryUtilImpl.parseCvsLogs(CvsRepositoryUtilImpl.java:153)
at com.atlassian.jira.web.action.admin.vcs.RepositoryActionSupport.testRepository(RepositoryActionSupport.java:285)
at com.atlassian.jira.web.action.admin.vcs.RepositoryActionSupport.checkRepository(RepositoryActionSupport.java:224)
at com.atlassian.jira.web.action.admin.vcs.RepositoryActionSupport.checkPathsAndRepository(RepositoryActionSupport.java:336)
at com.atlassian.jira.web.action.admin.vcs.RepositoryActionSupport.validateRepositoryParameters(RepositoryActionSupport.java:309)
at com.atlassian.jira.web.action.admin.vcs.AddRepository.doValidation(AddRepository.java:54)
at webwork.action.ActionSupport.validate(ActionSupport.java:373)
at webwork.action.ActionSupport.execute(ActionSupport.java:150)
at com.atlassian.jira.action.JiraActionSupport.execute(JiraActionSupport.java:46)
at webwork.dispatcher.GenericDispatcher.executeAction(GenericDispatcher.java:131)
at com.atlassian.jira.web.dispatcher.JiraServletDispatcher.service(JiraServletDispatcher.java:186)