test_read_delimited_bloc under test_core.py randomly fails.

[akharit]

Description

test_read_delimited_bloc under test_core.py randomly fails.

Reproduction Steps

** Enumerate the steps to reproduce the issue here:**
It is easily observed on seeing travis test logs where on any run, there is a chance of the test failing under one or more Python versions, though not consistently against any particular version.

Environment summary

SDK Version: What version of the SDK are you using? (pip show azure-datalake-store)
0.0.28

Python Version: What Python version are you using? Is it 64-bit or 32-bit?
Variable

OS Version: What OS and version are you using?
Linux,Windows

Shell Type: What shell are you using? (e.g. bash, cmd.exe, Bash on Windows)
bash, cmd.exe

[akharit]

Root cause is due to test case, and not the sdk. The test case has the file path
fn = '/tmp/test/a'

set as a fixed constant, which in the root folder, and does not use a relative path to randomly generated test_dir variable.
When running on travis for multiple versions simultaneously, a possible race condition develops where the file may be deleted by the same test case running for another python version.

Fix is to use one of the random path names. For example,
fn = a
where a has been defined previously as
a = posix(test_dir / 'a')

[akharit]

Fixed.