Agenda: Fix bug with tag inheritance

Agenda: Fix bug with tag inheritance

Jeff Mickey writes:

>  Hey all,
>
>  To reproduce:
>
>  * TODO Make Bicycle :project:workshop:
>  ** TODO Buy stuff
>  ** TODO Build stuff
>  ** TODO Test stuff
>
>  (setq org-use-tag-inheritance t)
>  (setq org-tags-exclude-from-inheritance '("project"))
>
>  <C-a m> to type in a match string to search, I type in "project"
>
>  I expected to see:
>  TODO Make Bicycle
>
>  I saw:
>  TODO Make Bicycle
>  .TODO Buy stuff
>  .TODO Build stuff
>  .TODO Test stuff
>
>  I assume this isn't what is supposed to happen.  I'm currently at work
>  so I can't investigate and provide a diff, but it seems like there
>  needs to be a check in org.el:10144:org-get-tags-at to remove tags
>  that are explicitly excluded from inheritance.

This commit fixes the bug.