Flaky travis builds on openbs/cstor

[kmova]

What steps did you take and what happened: Travis fails intermittently. It is hard to debug the cause for the failure by looking at the logs. Restarting on the build usually passes the build.

What did you expect to happen: The cause for build failure in travis should be easy to debug.

The output of the following commands and cstor pod logs will help us better understand what's going on: The logs from one of the failures are as follows:

• https://api.travis-ci.org/v3/job/706092122/log.txt
• https://api.travis-ci.org/v3/job/706092121/log.txt

[mittachaitu]

(abd_is_linear(zio->io_abd)) implies (abd_is_linear(data))
ASSERT at ../../module/zfs/zio.c:336:zio_push_transform()/home/travis/build/openebs/cstor/cmd/ztest/.libs/lt-ztest[0x40981f]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x11390)[0x7f6b916da390]
/lib/x86_64-linux-gnu/libc.so.6(gsignal+0x38)[0x7f6b91334428]
/lib/x86_64-linux-gnu/libc.so.6(abort+0x16a)[0x7f6b9133602a]
/home/travis/build/openebs/cstor/lib/libzpool/.libs/libzpool.so.2(+0x169a63)[0x7f6b921d4a63]
/home/travis/build/openebs/cstor/lib/libzpool/.libs/libzpool.so.2(+0x54360)[0x7f6b920bf360]
/home/travis/build/openebs/cstor/lib/libzpool/.libs/libzpool.so.2(+0x172b29)[0x7f6b921ddb29]
/home/travis/build/openebs/cstor/lib/libzpool/.libs/libzpool.so.2(zio_execute+0x128)[0x7f6b921d8e08]
/home/travis/build/openebs/cstor/lib/libzpool/.libs/libzpool.so.2(+0x42240)[0x7f6b920ad240]
/home/travis/build/openebs/cstor/lib/libzpool/.libs/libzpool.so.2(zk_thread_helper+0x12c)[0x7f6b920a92fc]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x76ba)[0x7f6b916d06ba]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7f6b9140641d]
child died with signal 6

Above is known assertion and the current workaround is to restart the Travis build. For more info: pool_travis.txt