bug fix and performance improve

Hi Paul,

The patch 4 can improve a lot on update.py (up to 98%), here is the testing data, please feel free to give your comments.

$ time update.py -b master --nofetch [--fullreload]

                   Before    Now       Reduced
No update:         276s      3.6s      98%
Partial update:    312s      87s       72%
Full repload:      1016s     980s      3%

Note:
* All of the testing are based on --nofetch

* "No update" means all layers on the branch is up-to-date, for example, when we run it twice, there is no update in the second run, so we only need about 3s now, which is the most common case when we use cron to run it per half an hour.

* "Partly update" means part of the layers have been updated.

* "Fullreload" means all of the layers have been updated.

// Robert

The following changes since commit 611c96883c35240d3c291951146154d828745774:

requirements.txt: use the most recent Django 1.8 version (2018-03-26 08:29:27 +1300)

are available in the git repository at:

git://git.pokylinux.org/poky-contrib rbt/layerindex
http://git.pokylinux.org/cgit.cgi//log/?h=rbt/layerindex

Robert Yang (4):
fixup! update: don't stop on unsatisfied layer dependencies update.py: add an option --timeout for lockfile update.py: print failed layers summary in the end update_layer.py: move layer validation to update.py (Performance
improve)

 layerindex/update.py       | 97 ++++++++++++++++++++++++++++++++++++++++++++--
 layerindex/update_layer.py | 39 ++-----------------
 layerindex/utils.py        | 14 +++++--
 3 files changed, 108 insertions(+), 42 deletions(-)

2.7.4