twbs/bootstrap — pull request #12674 by tlindig (2014-02-10 10:12:21+00:00)
Title: reuse popover variables to set popover arrow colors.

The arrow of a popover should often look like a fin of the box with same background and border color.
So I suggest to reuse this values to specify the arrow values.
IMHO it makes also more clear for what this variables are standing for.