[build-subsets.sh, build-ttf.sh] added SOURCE_DATE_EPOCH calcs from git commit date/time

to support reproducible builds

build-subsets.sh

@@ -14,6 +14,9 @@
 #
 # //////////////////////////////////////////////////////////////////////
 
+# set SOURCE_DATE_EPOCH to git commit date/time for reproducible builds
+SOURCE_DATE_EPOCH=$(git show -s --format=%ct HEAD)
+
 # default build tooling definitions
 TTFAH="$HOME/ttfautohint-build/local/bin/ttfautohint"
 FONTMAKE="pipenv run fontmake"

build-ttf.sh

@@ -13,6 +13,9 @@
 #
 # /////////////////////////////////////////////////////////////////
 
+# set SOURCE_DATE_EPOCH to git commit date/time for reproducible builds
+SOURCE_DATE_EPOCH=$(git show -s --format=%ct HEAD)
+
 # default build tooling definitions
 TTFAH="$HOME/ttfautohint-build/local/bin/ttfautohint"
 FONTMAKE="pipenv run fontmake"
@@ -137,6 +140,7 @@ if ! $FONTMAKE -u "source/Hack-BoldItalic.ufo" -o ttf
 	    exit 1
 fi
 
+
 # Desktop ttf font post build fixes
 
 # DSIG table fix with adapted fontbakery Python script