use getwd() to find path instead of "."
MODIFY
repo2docker/buildpacks/r.py
repo2docker/buildpacks/r.py
@@ -269,7 +269,7 @@ class RBuildPack(PythonBuildPack):
assemble_scripts += [
(
"${NB_USER}",
- 'R --quiet -e "devtools::install_git(\'.\')"'
+ 'R --quiet -e "devtools::install_local(getwd())"'
)
]

DELETE
tests/r/description-file/runtime.txt
-r-2018-02-05

use getwd() to find path instead of "."