Removal doesn't undo the activation thing

[tonyg]

So yesterday I fired up racket repl and was greeted with the warning that I wouldn't be getting any readline support. Fair enough. raco pkg install readline-gpl, and all is well.

Just now I wanted to see that warning again, so I raco pkg remove readline-gpl, and start up racket repl, only to be presented with

• no warning
• readline support

This doesn't seem quite right. Shouldn't removing the package put things back the way they were?

To reproduce

• fresh racket on a fresh OS with minimal libs (e.g. no libeditline?) - sufficient to provoke the warning, at any rate
• racket repl should warn about no readline support
• raco pkg install readline-gpl
• racket should give readline support
• raco pkg remove readline-gpl
• no change: still readline support, no warning

  Expected

Warning after raco pkg remove readline-gpl; No readline support after raco pkg remove readline-gpl.

[samth]

cc @LeifAndersen @mflatt

[mflatt]

This is a bug in raco setup, and I've pushed a repair.