[FIXED JENKINS-9532] 404 when clicking in the weather report column of a build that hasn't yet been run

HistoryWidget.

Some of our tags, such as <optionalBlock> and <dropdownList> involves grouping of sibling table rows, and controlling visibility of them. So when such tags nest to each other, the visibility updates need to be done carefully, or else the visibility could get out of sync with the model (imagine outer group is made visible while inner group is not visible --- if all the rows are simply enumerated and visibility changed, we end up making the inner group visible.)

The rowVisibilityGroup object in hudson-behavior.js is used to coordinate this activity, and this test ensures that it's working.

monitor fix.

marker.

[FIXED JENKINS-7537] reports indicate that exec(2) from multi-threaded app now works on Snow Leopard. Also see JENKINS-4012

this and the previous commit constitutes the fix.
Also added a test case.

The URL is used in many more places than just E-mail Notification, but people who do not send emails from Jenkins tend to overlook it and do not think it is a setting that will affect them.

so doesn't really belong here.. will add in wiki instead.