Fix a bug with Multiple Render Targets.

src/mesa/swrast/s_span.c

 /*
  * Mesa 3-D graphics library
  * Version:  7.5
  *
  * Copyright (C) 1999-2008  Brian Paul   All Rights Reserved.
  * Copyright (C) 2009  VMware, Inc.  All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
@@ skipping 1312 matching lines @@
          if (rb) {
             /* re-use one of the attribute array buffers for rgbaSave */
             GLchan (*rgbaSave)[4] = (GLchan (*)[4]) span->array->attribs[0];
             struct swrast_renderbuffer *srb = swrast_renderbuffer(rb);
             GLenum colorType = srb->ColorType;
 
             assert(colorType == GL_UNSIGNED_BYTE ||
                    colorType == GL_FLOAT);
 
             /* set span->array->rgba to colors for renderbuffer's datatype */
-            if (span->array->ChanType != colorType) {
-               convert_color_type(span, colorType, 0);
+            if (span->array->ChanType != colorType || multiFragOutputs) {
+               convert_color_type(span, colorType, buf);
             }
             else {
                if (span->array->ChanType == GL_UNSIGNED_BYTE) {
                   span->array->rgba = span->array->rgba8;
                }
                else {
                   span->array->rgba = (void *)
                      span->array->attribs[FRAG_ATTRIB_COL0];
                }
             }
@@ skipping 236 matching lines @@
       get_values(ctx, rb, span->end, span->array->x, span->array->y,
                  rbPixels, span->array->ChanType);
    }
    else {
       get_row(ctx, rb, span->end, span->x, span->y,
               rbPixels, span->array->ChanType);
    }
 
    return rbPixels;
 }