make install is broken

[robe]

Make install is broken. Seeing this on all the bots

Seems to be an issue since I flipped the switch, which is odd, cause I didn't even change to dropping the minor

 legacy .. failed (diff expected obtained: /projects/postgis/tmp/3.0.0dev_pg10_geos3.7.0dev_gdal2.2.4w64/test_50_diff)
-----------------------------------------------------------------------------
--- legacy_expected	2017-10-26 19:18:11.560448900 -0400
+++ /projects/postgis/tmp/3.0.0dev_pg10_geos3.7.0dev_gdal2.2.4w64/test_50_out	2018-08-29 12:42:35.641212200 -0400
@@ -1,21 +1,9691 @@
+\cd: could not change directory to "E:/jenkins/postgresql/rel/pg10w64gcc48/share/contrib/postgis-3.": No such file or directory
+psql:legacy.sql:11: \cd: could not change directory to "E:/jenkins/postgresql/rel/pg10w64gcc48/share/contrib/postgis-3.": No such file or directory
+psql:legacy.sql:11: \cd: could not change directory to "E:/jenkins/postgresql/rel/pg10w64gcc48/share/contrib/postgis-3.": No such file or directory
+psql:legacy.sql:11: \cd: could not change directory to "E:/jenkins/postgresql/rel/pg10w64gcc48/share/contrib/postgis-3.": No such file or directory

So perhaps something else in our code is causing it