shell: Fix prompt to support [env] prepended to second line.

.emacs.d/lisp/init-shell.el

@@ -36,7 +36,7 @@ prefix arg shell buffer doesn't exists, create it and switch to it."
   (set (make-variable-buffer-local 'comint-input-history-ignore)
        (regexp-opt '("^#" "^ " "^cd ")))
   (setq comint-prompt-regexp "^[^#$%>]*
-[#$%>] *"))
+[^#$%>]*[#$%>] *"))
 
 (add-hook 'shell-mode-hook 'ambrevar/shell-setup)
 
@@ -124,4 +124,6 @@ In normal circumstances this input is additionally filtered by
          (ambrevar/shell-prompt-begin-position))))))
 (define-key shell-mode-map (kbd "C-x n d") 'ambrevar/shell-narrow-to-prompt)
 
+(define-key shell-mode-map (kbd "C-x M-O") 'comint-truncate-buffer)
+
 (provide 'init-shell)