Modified the GDS read-in section of the magic tech file for

sky130 to remove the area of any actual metal coincident with the
corresponding fill block type from the fill block area.  Otherwise
the fill block will overwrite and obliterate the metal on read-in.
This solves the issue reported on the github issue tracker for
magic (issue 321).  NOTE:  There remains an issue that the
"fillblock" layer in magic does not symmetrically write out and
read back in;  however, this problem is due mostly to the poor
implementation of "fillblock".

VERSION

@@ -1 +1 @@
-1.0.491
+1.0.492

sky130/magic/sky130.tech

@@ -3957,22 +3957,32 @@ style  sky130 variants (),(vendor)
 # and FILLOBSM1,FILLOBSM2,FILLOBSM3,FILLOBSM4
 
 # Use the obstruction types for fill block on individual layers
- layer obsactive FILLOBSFOM,FILLOBSPOLY
+ templayer obspoly FILLOBSPOLY
+ and-not POLY
+
+ layer obsactive FILLOBSFOM
+ and-not DIFF,TAP
+ or obspoly
  labels FILLOBSFOM,FILLOBSPOLY
 
  layer obsm1 FILLOBSM1
+ and-not MET1
  labels FILLOBSM1
 
  layer obsm2 FILLOBSM2
+ and-not MET2
  labels FILLOBSM2
 
  layer obsm3 FILLOBSM3
+ and-not MET3
  labels FILLOBSM3
 
  layer obsm4 FILLOBSM4
+ and-not MET4
  labels FILLOBSM4
 
  layer obsm5 FILLOBSM5
+ and-not MET5
  labels FILLOBSM5
 
 # MOS Varactor