Also trying this on another machine…
2.12.1 does not seem to exist:
Setting gradle 2.14.1 as default.
Adams-MacBook-Pro:~ adamginsburg$ sdk install gradle 2.12.1
Stop! gradle 2.12.1 is not available. Possible causes:
* 2.12.1 is an invalid version
* gradle binaries are incompatible with Darwin
Adams-MacBook-Pro:~ adamginsburg$ sdk install gradle 2.12
Downloading: gradle 2.12
In progress...
######################################################################## 100.0%
Installing: gradle 2.12
Done installing!
Do you want gradle 2.12 to be set as default? (Y/n): Y
Setting gradle 2.12 as default.