SIGINT not being handled properly

Moved here from ardrone_autonomy.

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When sending a SIGINT to an ardrone_driver node, before a connection to the drone can be established (because it is switched off, for example), I get the following output:

[ardrone_driver-1] killing on exit
[ardrone_driver-1] escalating to SIGTERM
[ardrone_driver-1] escalating to SIGKILL
Shutdown errors:
 * process[ardrone_driver-1, pid 4142]: required SIGKILL. May still be running.

The package seems to be stuck in a getDroneVersion() call in ardronelib. Here's a backtrace:

Program received signal SIGINT, Interrupt.
0x00007f3dc0fa5720 in __connect_nocancel () at ../sysdeps/unix/syscall-template.S:81
81  in ../sysdeps/unix/syscall-template.S
(gdb) backtrace
#0  0x00007f3dc0fa5720 in __connect_nocancel ()
    at ../sysdeps/unix/syscall-template.S:81
#1  0x0000000000761fd7 in vp_com_open_socket ()
#2  0x000000000059bf12 in ftpConnect ()
#3  0x0000000000596715 in getDroneVersion ()
#4  0x00000000005150c2 in main (argc=0, argv=0x7fffff989f70)
    at /catkin_ws/src/ardrone_autonomy/src/ardrone_driver.cpp:804

I'm using ardrone_autonomy (1d3de8a333), which uses ardronelib 2f98702