ros::get-param in timer callback function never return

[furushchev]

In this code, timer-cb never end at ros::get-param.

(ros::roseus "aaa")

(defun timer-cb (event)
  (ros::ros-info "timer-cb")
  (setq *param* (ros::get-param "param" nil))
  (ros::ros-info "get-param: ~A" *param*))

(ros::create-timer 1.0 #'timer-cb)                                                                    
(ros::spin)

furushchev@pr1012:/tmp$ roseus hoge.l
configuring by "/home/furushchev/ros/indigo_parent/devel/share/euslisp/jskeus/eus//lib/eusrt.l"
;; readmacro ;; object ;; packsym ;; common ;; constants ;; stream ;; string ;; loader ;; pprint ;; p\
rocess ;; hashtab ;; array ;; mathtran ;; eusdebug ;; eusforeign ;; coordinates ;; tty ;; history ;; \
toplevel ;; trans ;; comp ;; builtins ;; par ;; intersection ;; geoclasses ;; geopack ;; geobody ;; p\
rimt ;; compose ;; polygon ;; viewing ;; viewport ;; viewsurface ;; hid ;; shadow ;; bodyrel ;; dda ;\
; helpsub ;; eushelp ;; xforeign ;; Xdecl ;; Xgraphics ;; Xcolor ;; Xeus ;; Xevent ;; Xpanel ;; Xitem\
 ;; Xtext ;; Xmenu ;; Xscroll ;; Xcanvas ;; Xtop ;; Xapplwin 
;; pixword ;; RGBHLS ;; convolve ;; piximage ;; pbmfile ;; image_correlation ;; oglforeign ;; gldecl \
;; glconst ;; glforeign ;; gluconst ;; gluforeign ;; glxconst ;; glxforeign ;; eglforeign ;; eglfunc \
;; glutil ;; gltexture ;; glprim ;; gleus ;; glview ;; toiv-undefined ;; fstringdouble irtmath irtuti\
l irtc irtgeoc irtgraph pgsql irtgeo euspqp pqp irtscene irtmodel irtdyna irtrobot irtsensor irtbvh i\
rtcollada irtpointcloud irtx eusjpeg euspng png irtimage irtglrgb 
;; extending gcstack 0x54a2dc0[16374] --> 0x58d7c40[32748] top=3d4c
irtgl irtglc irtviewer                                                                                
EusLisp 9.23(2bd8990 1.1.0) for Linux64 created on pr1012(Sat Dec 23 14:28:08 JST 2017)
roseus ;; loading roseus("1.6.3") on euslisp((9.23 pr1012 Sat Dec 23 14:28:08 JST 2017 2bd8990 1.1.0)\
)                                                                                                     
eustf roseus_c_util [ INFO] [1517987463.186017984] [/aaa_1517987462159617269:ros.roseus]: timer-cb
  C-c C-c  C-c C-z
[1]+  Stopped                 roseus hoge.l