All these combitions will now work:

<ui-select multiple>
<ui-select multiple="true">
<ui-select multiple="false">

This will solve:
https://github.com/angular-ui/ui-select/issues/217
Is there any way to change multiple selection mode at the run time
feat(choices): prevent calling $select.isActive/isDisabled when dropdown closed
fix(keys): should select active item and go to next control when pressing TAB
fix(keys): prevent dropdown to open with cmd key
Merge pull request #286 from angular-ui/fix-select-with-tab

Should select active item and go to next control when pressing TAB
Merge pull request #273 from angular-ui/perf_choices_active_disabled

feat(choices): prevent calling $select.isActive/isDisabled when dropdown...
Merge pull request #272 from jmcpeak/master

All these combinations will now work:
fix(choices): reset activeMatchIndex on blur
chore(build): v0.8.2
Remove bootstrap plunker demo from README