force testing .env with no newline and actually fix #1025 and #1026. closes #1063

plugins/build-env/pre-build

@@ -10,6 +10,7 @@ APP="$1"; IMAGE="dokku/$APP"; BUILD_ENV=""
 ! (grep -q CURL_TIMEOUT "$DOKKU_ROOT/ENV" > /dev/null 2>&1) && echo "export CURL_TIMEOUT=30" >> "$DOKKU_ROOT/ENV"
 
 if [[ -f "$DOKKU_ROOT/ENV" ]]; then
+  BUILD_ENV+=$'\n'
   BUILD_ENV+=$(< "$DOKKU_ROOT/ENV")
   BUILD_ENV+=$'\n'
 fi

tests/apps/ruby/.env

@@ -0,0 +1 @@
+export BUILDPACK_URL=https://github.com/heroku/heroku-buildpack-ruby#v129