Merge branch 'nd/log-decorate-color-head-arrow'

An entry "git log --decorate" for the tip of the current branch is
shown as "HEAD -> name" (where "name" is the name of the branch);
paint the arrow in the same color as "HEAD", not in the color for
commits.

* nd/log-decorate-color-head-arrow:
  log: decorate HEAD -> branch with the same color for arrow and HEAD

diff --cc log-tree.c
Simple merge