Makefile: do not needlessly update commitid.scad

diff --git a/Makefile b/Makefile
index 57ee94ffd06e30b665490359bf1723725f367377..9e879aba64a359ed74896b1d24093095454f52a7 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -33,7 +33,7 @@ AUTO_INCS = funcs.scad
 
 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))