Bug 922963

Description of problem:
Upgraded to today's F19 repos. 

When I go user-accounts, click on the user icon, click on "Take a photo", the webcam dialog appears. Once I click there on "Take a photo", I get a 
a white background on the whole background and I have to kill it manually.

Version-Release number of selected component (if applicable):
control-center 3.7.91-1. cheese 3.7.91-1.

Following thread seems stuck in v4l2 (will attach the full one):
Thread 4 (Thread 0x7f6bf8ff9700 (LWP 19932)):
#0  0x0000003e23eea9bf in __GI_ppoll (fds=0x7f6be001b780, nfds=2, timeout=<optimized out>, sigmask=sigmask@entry=0x0)
    at ../sysdeps/unix/sysv/linux/ppoll.c:56
        resultvar = 18446744073709551102
        oldtype = 0
        tval = {tv_sec = 140101296468048, tv_nsec = 266928158305}
        result = <optimized out>
#1  0x0000003e42c6cf5a in ppoll (__ss=0x0, __timeout=<optimized out>, __nfds=<optimized out>, __fds=<optimized out>) at /usr/include/bits/poll2.h:77
#2  gst_poll_wait (set=0x34396d0, timeout=timeout@entry=18446744073709551615) at gstpoll.c:1253
        ts = {tv_sec = 54726592, tv_nsec = 0}
        tsptr = <optimized out>
        mode = GST_POLL_MODE_PPOLL
        restarting = 0
        is_timer = <optimized out>
        res = -1
        old_waiting = <optimized out>
        __PRETTY_FUNCTION__ = "gst_poll_wait"
#3  0x00007f6c0d651fc4 in gst_v4l2_object_poll (v4l2object=v4l2object@entry=0x3446cf0) at gstv4l2bufferpool.c:521
        ret = <optimized out>
#4  0x00007f6c0d65246d in gst_v4l2_object_poll (v4l2object=0x3446cf0) at gstv4l2bufferpool.c:519
#5  gst_v4l2_buffer_pool_dqbuf (pool=pool@entry=0x2e14b70, buffer=buffer@entry=0x7f6bf8ff88b8) at gstv4l2bufferpool.c:609
        res = <optimized out>
        outbuf = <optimized out>
        vbuffer = {index = 3758239824, type = 32619, bytesused = 648102910, flags = 62, field = 54727744, timestamp = {tv_sec = 0,
            tv_usec = 54718768}, timecode = {type = 55408272, flags = 0, frames = 80 'P', seconds = 48 '0', minutes = 2 '\002', hours = 224 '\340',
            userbits = "k\177\000"}, sequence = 640185953, memory = 62, m = {offset = 3758239824, userptr = 140101296468048,
            planes = 0x7f6be0023050, fd = -536727472}, length = 1120251177, reserved2 = 62, reserved = 55510608}
        obj = 0x3446cf0
        timestamp = <optimized out>
        __FUNCTION__ = "gst_v4l2_buffer_pool_dqbuf"
#6  0x00007f6c0d6534d6 in gst_v4l2_buffer_pool_acquire_buffer (bpool=0x2e14b70, buffer=0x7f6bf8ff88b8, params=0x0) at gstv4l2bufferpool.c:749
        ret = <optimized out>
        pool = 0x2e14b70
        obj = 0x3446cf0
        __FUNCTION__ = "gst_v4l2_buffer_pool_acquire_buffer"
#7  0x0000003e42c377f2 in gst_buffer_pool_acquire_buffer (pool=0x2e14b70, buffer=0x7f6bf8ff88b8, params=0x0) at gstbufferpool.c:1100
        pclass = <optimized out>
        result = <optimized out>
        __PRETTY_FUNCTION__ = "gst_buffer_pool_acquire_buffer"
#8  0x0000003e44e25dc1 in gst_base_src_default_create (src=0x2e0a790, offset=18446744073709551615, size=4096, buffer=0x7f6bf8ff89e0)
    at gstbasesrc.c:1423
        bclass = 0x2e058e0
        ret = <optimized out>
        res_buf = 0xffffffffffffffff
        __PRETTY_FUNCTION__ = "gst_base_src_default_create"