bug#30091: 25.3; Trying to go to non-existent info file puts the cursor in *info* buffer, not mini buffer

[Tim Landscheidt]

(Under Fedora 26 and X, also with master,) to reproduce:

- "emacs -Q",
- C-h i for *info* buffer,
- g for "Go to node:",
- (does-not-exist) RET.

Result:

- Mini buffer says: "Info file does-not-exist does not
  exist",
- then switches back to "Go to node: (does-not-exist)",
- but cursor is put in *info* buffer, thus requiring to C-x
  o to reenter mini buffer to correct (or abort).

Expected result:

- The cursor should be in the mini buffer, not in *info*.