"wrong type arguments: stringp sh"

I'm using ob-ipython-20180224.953, and I've seen this error ("wrong type arguments: stringp sh") while doing something completely unrelated to ipython. I've traced it, and it ends up in the following code:
```
(defun ob-ipython--configure-kernel (kernel-lang)
"Configure org mode to use specified kernel."
(let* ((kernel (car kernel-lang))
(language (cdr kernel-lang))
(jupyter-lang (concat "jupyter-" language))
(mode (intern (or (cdr (assoc language org-src-lang-modes))
(replace-regexp-in-string "[0-9]*" "" language))))
(header-args (intern (concat "org-babel-default-header-args:" jupyter-lang))))
...
```
It seems like most kernel names are like "Julia-0.6", and not directly found in `org-src-lang-modes`, thus their names are going through `(replace-regexp-in-string ...)` branch. But in my case I has kernel "bash", installed in my jupyter, and this kernel name is as-is present in `org-src-lang-modes`. And here is the catch: this map contains languages as _symbols_ not strings, but intern expect string, not symbol.

Personally, I've fixed it in my copy by just add `(symbol-name ..)` call around `(cdr (assoc language org-src-lang-modes))`. Probably, even better solution would be to move `(intern ..)` to be only around `(replace-regexp-in-string ...)`, since it is not needed in first branch.