Cobblestone Wall With Blocks On Top Shows Black Light On Its North Side With Maximum Smooth Lighting

Confirmed with any kind of blocks on top, this issue only appears on maximum smooth lighting on the north side of the wall (south from player's perspective).

I can't seem to reproduce anymore as of 13w26a.

Still seeing it on the north side of the wall.

I've looked at the code and seen that the problem (and the solution) is a careless mistakes

//  package net.minecraft.src;
//  ...
//  public class RenderBlocks {
//    ...
//    public boolean renderBlockWithAmbientOcclusion(Block par1Block, int par2, int par3, int par4, float par5, float par6, float par7) {
//      ...
//      if (this.renderAllFaces || par1Block.shouldSideBeRendered(this.blockAccess, par2, par3, par4 - 1, 2)) {
//        ...
          /* START OF OLD CODE *
          var9 = (float)((double)var22 * this.renderMaxY * (1.0D - this.renderMinX) + (double)var23 * this.renderMinY * this.renderMinX + (double)var24 * (1.0D - this.renderMaxY) * this.renderMinX + (double)var25 * (1.0D - this.renderMaxY) * (1.0D - this.renderMinX));
          * END OF OLD CODE */
          /* START OF NEW CODE *
          var9 = (float)((double)var22 * this.renderMaxY * (1.0D - this.renderMinX) + (double)var23 * this.renderMaxY * this.renderMinX + (double)var24 * (1.0D - this.renderMaxY) * this.renderMinX + (double)var25 * (1.0D - this.renderMaxY) * (1.0D - this.renderMinX));
          /* END OF NEW CODE */
          var10 = (float)((double)var22 * this.renderMaxY * (1.0D - this.renderMaxX) + (double)var23 * this.renderMaxY * this.renderMaxX + (double)var24 * (1.0D - this.renderMaxY) * this.renderMaxX + (double)var25 * (1.0D - this.renderMaxY) * (1.0D - this.renderMaxX));
          var11 = (float)((double)var22 * this.renderMinY * (1.0D - this.renderMaxX) + (double)var23 * this.renderMinY * this.renderMaxX + (double)var24 * (1.0D - this.renderMinY) * this.renderMaxX + (double)var25 * (1.0D - this.renderMinY) * (1.0D - this.renderMaxX));
          var12 = (float)((double)var22 * this.renderMinY * (1.0D - this.renderMinX) + (double)var23 * this.renderMinY * this.renderMinX + (double)var24 * (1.0D - this.renderMinY) * this.renderMinX + (double)var25 * (1.0D - this.renderMinY) * (1.0D - this.renderMinX));
//        ...
//      }
//      ...
//    }
//    ...
//  }

If you look at var10, var11 and var12 lines, each line uses this.renderMaxY or this.renderMinY, not both, same for this.renderMaxX or this.renderMinX.
the var9 line uses three this.renderMaxY and one this.renderMinY, I've tried to change that to use only this.renderMaxY on that line, and it solved the problem.

This thing with MC-190 solve the corner stair problem.

Concern 1.6.2 !

Concern 13w37b !!!

Confirmed in 13w41b !

bkw.class is a bugfix modification for Minecraft 13w42b for MC-15189 and MC-190

Please make a custom 13w42b version and install that file in the jar file

Concern 13w43a !

Concern 1.7.1 !

Totally fixed!