Fix handling of Python/Guile commands with arguments in gdb-mi.el

* lisp/progmodes/gdb-mi.el (gdb-python-guile-commands-regexp): New
variable.
(gdb-control-commands-regexp): Use it.
(gdb-send): Don't increment gdb-control-level if the command
matches gdb-python-guile-commands-regexp and has non-empty
arguments.  Reported by David Boles <boles@ieee.org> in
http://lists.gnu.org/archive/html/emacs-devel/2017-06/msg00009.html.

lisp/progmodes/gdb-mi.el

@@ -1767,13 +1767,17 @@ static char *magick[] = {
   :group 'gdb)
 
 
+(defvar gdb-python-guile-commands-regexp
+  "python\\|python-interactive\\|pi\\|guile\\|guile-repl\\|gr"
+  "Regexp that matches Python and Guile commands supported by GDB.")
+
 (defvar gdb-control-commands-regexp
   (concat
    "^\\("
    "commands\\|if\\|while\\|define\\|document\\|"
-   "python\\|python-interactive\\|pi\\|guile\\|guile-repl\\|gr\\|"
-   "while-stepping\\|stepping\\|ws\\|actions"
-   "\\)\\([[:blank:]]+.*\\)?$")
+   gdb-python-guile-commands-regexp
+   "\\|while-stepping\\|stepping\\|ws\\|actions"
+   "\\)\\([[:blank:]]+\\([^[:blank:]]*\\)\\)?$")
   "Regexp matching GDB commands that enter a recursive reading loop.
 As long as GDB is in the recursive reading loop, it does not expect
 commands to be prefixed by \"-interpreter-exec console\".")
@@ -1831,8 +1835,17 @@ commands to be prefixed by \"-interpreter-exec console\".")
 	       (> gdb-control-level 0))
 	  (setq gdb-control-level (1- gdb-control-level)))
       (setq gdb-continuation nil)))
-  (if (string-match gdb-control-commands-regexp string)
-      (setq gdb-control-level (1+ gdb-control-level))))
+  ;; Python and Guile commands that have an argument don't enter the
+  ;; recursive reading loop.
+  (let* ((control-command-p (string-match gdb-control-commands-regexp string))
+         (command-arg (match-string 3 string))
+         (python-or-guile-p (string-match gdb-python-guile-commands-regexp
+                                          string)))
+    (if (and control-command-p
+             (or (not python-or-guile-p)
+                 (null command-arg)
+                 (zerop (length command-arg))))
+        (setq gdb-control-level (1+ gdb-control-level)))))
 
 (defun gdb-mi-quote (string)
   "Return STRING quoted properly as an MI argument.