I have a USB camera on a Thinkpad T410 laptop, detected as:
uvcvideo: Found UVC 1.00 device Integrated Camera (17ef:480f)

Without this patch, v4l2src will fail to output anything the second time
it's used, unless different parameters are requested.

I guess some kind of way to make this optional has to be decided, as
applying this patch as is will revert to the 'slow setup' behavior this
skip was supposed to avoid (see f06b105058e73162275b50bdba89c6791e218d03).

For a log of that second-time-wedges with GST_DEBUG=v4l2src:5:

Setting pipeline to PAUSED ...
0:00:00.100190064 13521      0x24ec0a0 INFO                 v4l2src gstv4l2src.c:604:gst_v4l2src_get_caps:<v4l2src0> probed caps: video/x-raw-yuv, format=(fourcc)YUY2, width=(int)1600, height=(
0:00:00.104554710 13521      0x24ec0a0 DEBUG                v4l2src gstv4l2src.c:442:gst_v4l2src_negotiate:<v4l2src0> caps of src: video/x-raw-yuv, format=(fourcc)YUY2, width=(int)1600, height=
0:00:00.105263978 13521      0x24ec0a0 DEBUG                v4l2src gstv4l2src.c:443:gst_v4l2src_negotiate:<v4l2src0> thiscaps: video/x-raw-yuv, format=(fourcc)YUY2, width=(int)1600, height=(in
0:00:00.112320210 13521      0x24ec0a0 DEBUG                v4l2src gstv4l2src.c:451:gst_v4l2src_negotiate:<v4l2src0> caps of peer: video/x-raw-yuv, format=(fourcc)YUY2, width=(int)640, height=
0:00:00.112386694 13521      0x24ec0a0 DEBUG                v4l2src gstv4l2src.c:452:gst_v4l2src_negotiate:<v4l2src0> peercaps: video/x-raw-yuv, format=(fourcc)YUY2, width=(int)640, height=(int
0:00:00.112441939 13521      0x24ec0a0 DEBUG                v4l2src gstv4l2src.c:462:gst_v4l2src_negotiate:<v4l2src0> peer: video/x-raw-yuv, format=(fourcc)YUY2, width=(int)640, height=(int)480
0:00:00.112465517 13521      0x24ec0a0 DEBUG                v4l2src gstv4l2src.c:463:gst_v4l2src_negotiate:<v4l2src0> ipcaps: video/x-raw-yuv, format=(fourcc)YUY2, width=(int)640, height=(int)4
0:00:00.112528035 13521      0x24ec0a0 DEBUG                v4l2src gstv4l2src.c:475:gst_v4l2src_negotiate:<v4l2src0> intersect: video/x-raw-yuv, format=(fourcc)YUY2, width=(int)640, height=(in
0:00:00.112563235 13521      0x24ec0a0 DEBUG                v4l2src gstv4l2src.c:476:gst_v4l2src_negotiate:<v4l2src0> icaps: video/x-raw-yuv, format=(fourcc)YUY2, width=(int)640, height=(int)48
0:00:00.112655682 13521      0x24ec0a0 DEBUG                v4l2src gstv4l2src.c:530:gst_v4l2src_negotiate:<v4l2src0> fixated to: video/x-raw-yuv, format=(fourcc)YUY2, width=(int)640, height=(i
0:00:00.112683884 13521      0x24ec0a0 DEBUG                v4l2src gstv4l2src.c:531:gst_v4l2src_negotiate:<v4l2src0> caps: video/x-raw-yuv, format=(fourcc)YUY2, width=(int)640, height=(int)480
0:00:00.112717171 13521      0x24ec0a0 DEBUG                v4l2src gstv4l2src.c:642:gst_v4l2src_set_caps:<v4l2src0> trying to set_capture 640x480 at 30/1 fps, format YUV 4:2:2 (YUYV)
0:00:00.112736696 13521      0x24ec0a0 DEBUG                v4l2src v4l2src_calls.c:232:gst_v4l2src_set_capture:<v4l2src0> Desired framerate: 30/1
0:00:00.112755935 13521      0x24ec0a0 DEBUG                v4l2src v4l2src_calls.c:246:gst_v4l2src_set_capture:<v4l2src0> Desired framerate already set
0:00:00.112768248 13521      0x24ec0a0 INFO                 v4l2src v4l2src_calls.c:285:gst_v4l2src_set_capture:<v4l2src0> Set framerate to 30/1 and duration to 0:00:00.033333333
0:00:00.112781742 13521      0x24ec0a0 DEBUG                v4l2src v4l2src_calls.c:299:gst_v4l2src_capture_init:<v4l2src0> initializing the capture system
0:00:00.112793369 13521      0x24ec0a0 LOG                  v4l2src v4l2src_calls.c:307:gst_v4l2src_capture_init:<v4l2src0> initiating buffer pool
0:00:00.113401067 13521      0x24ec0a0 INFO                 v4l2src v4l2src_calls.c:314:gst_v4l2src_capture_init:<v4l2src0> capturing buffers via mmap()
0:00:00.113420878 13521      0x24ec0a0 DEBUG                v4l2src v4l2src_calls.c:361:gst_v4l2src_capture_start:<v4l2src0> starting the capturing
/GstPipeline:pipeline0/GstV4l2Src:v4l2src0.GstPad:src: caps = video/x-raw-yuv, format=(fourcc)YUY2, width=(int)640, height=(int)480, interlaced=(boolean)false, framerate=(fraction)30/1
0:00:00.114397748 13521      0x24ec0a0 LOG                  v4l2src gstv4l2src.c:756:gst_v4l2src_unlock_stop:<v4l2src0> No longer flushing
Pipeline is live and does not need PREROLL ...
Setting pipeline to PLAYING ...
0:00:00.115094038 13521      0x24ec0a0 LOG                  v4l2src gstv4l2src.c:756:gst_v4l2src_unlock_stop:<v4l2src0> No longer flushing
0:00:00.115152020 13521      0x264b4a0 DEBUG                v4l2src v4l2src_calls.c:110:gst_v4l2src_grab_frame:<v4l2src0> grab frame
Caught interrupt -- handling interrupt.
Interrupt: Stopping pipeline ...
Execution ended after 4242922372 ns.
Setting pipeline to PAUSED ...
0:00:04.358147486 13521      0x24ec0a0 LOG                  v4l2src gstv4l2src.c:745:gst_v4l2src_unlock:<v4l2src0> Flushing
0:00:04.358251658 13521      0x264b4a0 DEBUG                v4l2src v4l2src_calls.c:191:gst_v4l2src_grab_frame: stop called
Setting pipeline to READY ...
0:00:04.358531593 13521      0x24ec0a0 LOG                  v4l2src gstv4l2src.c:745:gst_v4l2src_unlock:<v4l2src0> Flushing
0:00:04.358550519 13521      0x24ec0a0 LOG                  v4l2src gstv4l2src.c:756:gst_v4l2src_unlock_stop:<v4l2src0> No longer flushing
0:00:04.358682347 13521      0x24ec0a0 DEBUG                v4l2src v4l2src_calls.c:390:gst_v4l2src_capture_stop:<v4l2src0> stopping capturing
0:00:04.383784158 13521      0x24ec0a0 DEBUG                v4l2src v4l2src_calls.c:424:gst_v4l2src_capture_deinit:<v4l2src0> deinitting capture system
/GstPipeline:pipeline0/GstV4l2Src:v4l2src0.GstPad:src: caps = NULL
Setting pipeline to NULL ...
Freeing pipeline ...