scripts: dbgbmap[d3].py: Limited block conflicts to mismatched types

Block conflict detection was originally implemented with non-dags in
mind. But now that dags are allowed, we shouldn't treat them as errors!

Instead, we only report blocks as conflicts if multiple references have
mismatching types.

This should still be very useful for debugging the upcoming bmap work.

scripts/dbgbmap.py

@@ -4603,7 +4603,12 @@ def main_(ring, disk, mroots=None, *,
                 # check for some common issues
 
                 # block conflict?
-                if b in bmap and bmap[b].type != 'unused':
+                #
+                # note we can't compare more than types due to different
+                # trunks, slicing, etc
+                if (b in bmap
+                        and bmap[b].type != 'unused'
+                        and bmap[b].type != type):
                     if bmap[b].type == 'conflict':
                         bmap[b].value.append(child)
                     else: