GHA: Install the 'future' develop branch - take 2

Author: HenrikBengtsson

.github/workflows/R-CMD-check.yaml

@@ -64,7 +64,8 @@ jobs:
 
       - name: Test with specific future version?
         run: |
-          future_version <- Sys.getenv("R_FUTURE_VERSION", "develop")
+          future_version <- Sys.getenv("R_FUTURE_VERSION")
+          if (!nzchar(future_version)) future_version <- "develop"
           if (nzchar(future_version)) {
             install.packages("remotes")
             remotes::install_github("futureverse/future", ref=future_version)