The branch removed in this patch handled color format A1R5G5B5 specially
when creating a texture from a TGA type 1 file, i.e. an image that has a
colormap. It did not handle the 1-bit alpha channel correctly, rendering
transparent pixels black instead.
Since the colormap is converted to A8R8G8B8 earlier anyways, the code
for the general case is able to handle this scenario already – at the
expense of making the created texture use twice as much GPU memory as
necessary.