Fix REPL prompt corruption

For some reason, `pop-to-buffer` with Emacs 25.1 after `make-comint`
results in corrupted prompt with strange ANSI control sequence.

For example, when feeding `class Foo {}` and enter key, the input is echoed
with the following character sequence

~~~
class Foo {}^[[1G^[[2m  1> ^[[22m^[[18G
~~~

which would be interpreted by a terminal like this

~~~
  1>  Foo {}
~~~

This is not desirable.

FYI, each sequence means as follows:

|sequence |meaning          |
|---------|-----------------|
|`^[[1G`  |Goto 1st column  |
|`^[[2m`  |Use faint color  |
|`^[[22m` |Use normal color |
|`^[[18G` |Goto 18th column |

Curiously, while invoking `swift` command from `shell` mode works fine,
it will be corrupted with the following steps:

1. Start `shell` mode.
2. Type `M-x`.
3. Cancel the minibuffer with `C-g`.
4. Invoke `swift` command from the shell.

I could not find the cause nor why this workaround works.

Author: taku0

swift-mode-repl.el

@@ -61,17 +61,20 @@ Runs the hook `swift-repl-mode-hook' \(after the `comint-mode-hook' is run).
    (list (if current-prefix-arg
              (read-string "Run swift REPL: " swift-mode:repl-executable)
            swift-mode:repl-executable)))
-  (unless (comint-check-proc (concat "*" cmd "*"))
-    (save-excursion
-      (let ((cmdlist (split-string cmd)))
-        (set-buffer
-         (apply 'make-comint cmd (car cmdlist) nil (cdr cmdlist)))
-        (swift-repl-mode))))
-  (setq-local swift-mode:repl-executable cmd)
-  (setq-local swift-mode:repl-buffer (concat "*" cmd "*"))
-  (setq-default swift-mode:repl-buffer swift-mode:repl-buffer)
-  (unless dont-switch
-    (pop-to-buffer swift-mode:repl-buffer)))
+  (let ((original-buffer (current-buffer))
+        (buffer (get-buffer-create (concat "*" cmd "*"))))
+    (unless dont-switch
+      (pop-to-buffer buffer))
+    (unless (comint-check-proc (concat "*" cmd "*"))
+      (save-excursion
+        (let ((cmdlist (split-string cmd)))
+          (apply 'make-comint-in-buffer
+                 cmd buffer (car cmdlist) nil (cdr cmdlist))
+          (swift-repl-mode))))
+    (with-current-buffer original-buffer
+      (setq-local swift-mode:repl-executable cmd)
+      (setq-local swift-mode:repl-buffer (concat "*" cmd "*"))
+      (setq-default swift-mode:repl-buffer swift-mode:repl-buffer))))
 
 ;;;###autoload
 (defalias 'run-swift 'swift-mode:run-repl)