[luatex] Problems with LuaTeX 1.0.8

[Jeremie Knuesel]

> I get differences also without luaotfload and with
>
> \font\tenrm=phvr8t at 10bp

Hi, I did more tests with Patrick's font expansion example and the
phvr8t font, and it seems that this other change of behavior indeed
comes from revision 6844 from the experimental branch. More precisely,
the following change is responsible:

diff -wu source/texk/web2c/luatexdir/tex/_linebreak.w
source/texk/web2c/luatexdir/tex/linebreak.c

[... lots of changes...]
@@ -1319,55 +1579,67 @@
                     shortfall -= (total_font_stretch + margin_kern_stretch);
             } else if ((shortfall < 0) && ((total_font_shrink +
margin_kern_shrink) > 0)) {
                 if ((total_font_shrink + margin_kern_shrink) > -shortfall)
-                    shortfall = -((total_font_shrink +
margin_kern_shrink) / (max_shrink_ratio / cur_font_step)) / 2;
+                    shortfall -= ((total_font_shrink +
margin_kern_shrink) / (max_shrink_ratio / cur_font_step)) / 2;
                 else
                     shortfall += (total_font_shrink + margin_kern_shrink);
             }
         }

Manually reverting this particular change brings back the old behavior.

Jeremie