Upgrade 1.599 to Jenkins 1.609.3 Migration (build number id)

[khmarbaise]

Hi,

i have upgraded a Jenkins version from 1.599 to 1.609.3 first i was not astonished that the build number ID's migration has started...but today i needed to restart Jenkins an other time and found that
during the start an other migration has taken place. Furthermore based on the information in JIRA etc. the migration would have taken place in 1.599 upgrade already...

Feb 22, 2016 5:59:57 PM jenkins.model.RunIdMigrator migrate
Information: Migrating build records in /.../jenkins/jobs/JOBXXX/builds
Feb 22, 2016 5:59:58 PM jenkins.model.RunIdMigrator doMigrate
Warnung: found unexpected dir lastUnstableBuild
Feb 22, 2016 5:59:58 PM jenkins.model.RunIdMigrator doMigrate
Warnung: found unexpected dir lastSuccessfulBuild

I thought the process was a one time process and shouldn't run a second time...

I have two question concerning this:

Under which circumstance the migration process is triggered (what triggers the migration process) and
how can i prevent that?

Kind regards
Karl Heinz Marbaise