Add CRAN-RELEASE to .Rbuildignore

Fixes #1711

NEWS.md

@@ -1,7 +1,9 @@
 # devtools 1.13.3.9000
 
+* The CRAN-RELEASE file is now added to .Rbuildignore (#1711)
+
 * The `lang` argument to `spell_check()` was removed, for compatibility with
-  [spelling](https://CRAN.R-project.org/package=spelling) v1.1.
+  [spelling](https://CRAN.R-project.org/package=spelling) v1.1. (#1715)
 
 * `check()` and `check_built()` now have an `error_on` argument to specify if
   they should throw an error on check failures. When run non-interactively this

R/release.r

@@ -357,4 +357,5 @@ flag_release <- function(pkg = ".") {
     "Once it is accepted, delete this file and tag the release (commit ", sha, ")."
   )
   writeLines(msg, file.path(pkg$path, "CRAN-RELEASE"))
+  usethis::use_build_ignore("CRAN-RELEASE")
 }