Merge pull request #3520 from rocker-org/master

upgrade r-base to R 3.4.2 released last Thursday

library/r-base

@@ -1,5 +1,5 @@
 # maintainer: "Carl Boettiger" <[email protected]> (@cboettig)
 # maintainer: "Dirk Eddelbuettel" <[email protected]> (@eddelbuettel)
 
-3.4.1: git://github.com/rocker-org/rocker@541002c788eff3ffce85c16072365bf2bc8bdf67 r-base
-latest: git://github.com/rocker-org/rocker@541002c788eff3ffce85c16072365bf2bc8bdf67 r-base
+3.4.2: git://github.com/rocker-org/rocker@eeeeac041f639377acb9320e6cb1c3154f160dfe r-base
+latest: git://github.com/rocker-org/rocker@eeeeac041f639377acb9320e6cb1c3154f160dfe r-base