default: autoincs scads
-$(shell set -xe; ./commitid.scad.pl >commitid.scad.tmp; mv -f commitid.scad.tmp commitid.scad )
+$(shell set -xe; ./commitid.scad.pl >commitid.scad.tmp; cmp commitid.scad.tmp commitid.scad || mv -f commitid.scad.tmp commitid.scad )
autoincs: $(AUTO_INCS)
scads: $(addsuffix .auto.scad, $(AUTO_TOPLEVELS))