userpref_get_config_dir() segfaults when $HOME is undefined

When I plug in my iPod Touch (4th gen.), upowerd crashes with the following stack trace. I have libimobiledevice-1.1.4 and UPower-0.9.15 installed.

Program received signal SIGSEGV, Segmentation fault.
__strcpy_chk () at ../sysdeps/x86_64/strcpy_chk.S:71
71      ../sysdeps/x86_64/strcpy_chk.S: File o directory non esistente.

(gdb) bt
#0  __strcpy_chk () at ../sysdeps/x86_64/strcpy_chk.S:71
#1  0x00007fdc47ee4eb8 in strcpy (__src=<optimized out>, __dest=0x7fdc480f5640 "") at /usr/include/bits/string3.h:105
#2  userpref_get_config_dir () at userpref.c:128
#3  0x00007fdc47ee55b4 in userpref_get_host_id (host_id=0x7fff6bdc8760) at userpref.c:406
#4  0x00007fdc47ee8d7d in lockdownd_client_new_with_handshake (device=<optimized out>, client=0x7fff6bdc87f0, label=<optimized out>) at lockdown.c:717
#5  0x0000000000412deb in up_device_idevice_coldplug (device=0x15cb540) at up-device-idevice.c:105
#6  0x000000000040b069 in up_device_coldplug (device=0x15cb540, daemon=<optimized out>, native=0x15c9230) at up-device.c:548
#7  0x00000000004119cb in up_backend_device_new (native=0x15c9230, backend=0x15afcf0) at up-backend.c:128
#8  up_backend_device_add (backend=0x15afcf0, native=0x15c9230) at up-backend.c:229
#9  0x00007fdc48425aa2 in g_closure_invoke (closure=0x15b7af0, return_value=0x0, n_param_values=3, param_values=0x7fff6bdc8a90, invocation_hint=<optimized out>) at gclosure.c:777
#10 0x00007fdc48436c5b in signal_emit_unlocked_R (node=<optimized out>, detail=0, instance=0x159cc40, emission_return=0x0, instance_and_params=0x7fff6bdc8a90) at gsignal.c:3547
#11 0x00007fdc4843eecd in g_signal_emit_valist (instance=<optimized out>, signal_id=<optimized out>, detail=0, var_args=<optimized out>) at gsignal.c:3296
#12 0x00007fdc4843f053 in g_signal_emit (instance=<optimized out>, signal_id=<optimized out>, detail=<optimized out>) at gsignal.c:3352
#13 0x00007fdc48667a73 in monitor_event (source=<optimized out>, condition=<optimized out>, data=0x159cc40) at src/gudev/gudevclient.c:105
#14 0x00007fdc4813d579 in g_main_dispatch (context=0x1597580) at gmain.c:2515
#15 g_main_context_dispatch (context=0x1597580) at gmain.c:3052
#16 0x00007fdc4813d938 in g_main_context_iterate (context=0x1597580, block=1, dispatch=1, self=<optimized out>) at gmain.c:3123
#17 0x00007fdc4813dd2a in g_main_loop_run (loop=0x15b6380) at gmain.c:3317
#18 0x0000000000411149 in main (argc=1, argv=0x7fff6bdc9168) at up-main.c:308

(gdb) f 2
#2  userpref_get_config_dir () at userpref.c:128
128                     strcpy(__config_dir, cdir);

The relevant code is:

        const char *cdir = getenv("XDG_CONFIG_HOME");
        if (!cdir) {
                cdir = getenv("HOME");
                strcpy(__config_dir, cdir);

It appears that both XDG_CONFIG_HOME and HOME are undefined in the environment, thus cdir is NULL and strcpy() crashes. This is a regression introduced with the glib dependency removal.