tidyverse:latest uses today as BUILD_DATE, tidyverse:3.3.2 uses fixed date

verse/Dockerfile builds on latest, verse/Dockerfile:3.3.2 builds on fixed date from tidyverse:3.3.2

Makefile

 R_VERSION=3.3.2
+BUILD_DATE=2016-11-08
 
 r-ver: .PHONY 
 	make -C r-ver/ latest
@@ -15,8 +16,9 @@ all:
 sync:
 	cp rstudio/Dockerfile rstudio/${R_VERSION}/Dockerfile
 	cp tidyverse/Dockerfile tidyverse/${R_VERSION}/Dockerfile
+	sed -i 's/ARG BUILD_DATE/ARG BUILD_DATE\nENV BUILD_DATE \$\{BUILD_DATE:-${BUILD_DATE}\}/' tidyverse/${R_VERSION}/Dockerfile
 	cp verse/Dockerfile verse/${R_VERSION}/Dockerfile
-
+	sed -i 's/tidyverse:latest/tidyverse:${R_VERSION}/' verse/${R_VERSION}/Dockerfile
 
 .PHONY:
 	echo "Building Rocker versioned images locally...\n"

tidyverse/3.3.2/Dockerfile

 FROM rocker/rstudio:3.3.2
 
 ARG BUILD_DATE
+ENV BUILD_DATE {BUILD_DATE:-2016-11-08}
 RUN apt-get update -qq && apt-get -y --no-install-recommends install \
   libxml2-dev \
   libsqlite-dev \

verse/Dockerfile

-FROM rocker/tidyverse:3.3.2
+FROM rocker/tidyverse:latest
 MAINTAINER "Carl Boettiger" cboettig@ropensci.org
 
 ## Add LaTeX, rticles and bookdown support