The config for git-gutter currently sets custom fringe bitmaps which
are optimized for half-width fringes.
I think that's an arbitrary choice. There's no spacemacs option which
enables half-width fringes and as far as I can tell, we don't optimize
for half-width fringes anywhere else. So we should optimize the
package defaults for the spacemacs default of full-size fringes.
If users set half-width fringes manually, they can customize the
bitmaps manually. Even if they don't, the bitmaps are still visible,
they just don't look as nice.
1bd5428360