Add commit metadata that expand in git archive.

pavoljuhas · pavoljuhas · commit 7f95e59db41a · 2017-06-20T14:29:12.000-04:00
diff --git a/.gitattributes b/.gitattributes
@@ -3,3 +3,4 @@
 /.travis*  export-ignore
 /conda-recipe/  export-ignore
 /doc  export-ignore
+gitarchive.cfg  export-subst
diff --git a/site_scons/gitarchive.cfg b/site_scons/gitarchive.cfg
@@ -0,0 +1,4 @@
+[DEFAULT]
+commit = $Format:%H$
+date = $Format:%ai$
+refnames = $Format:%D$
