HOTFIX: Fix unicode error in merge script.

[pwendell]

The merge script builds up a big command array and sometimes
this contains both unicode and ascii strings. This doesn't work
if you try to join them into a single string. Longer term a solution
is to go and make sure the source of all strings is unicode.

This patch provides a simpler solution... just print the array
rather than joining. I actually prefer printing an array here
anyways since joining on spaces is lossy in the case of arguments
that themselves contain spaces.

[SparkQA]

QA tests have started for PR 2645 at commit b26026f.

• This patch merges cleanly.

[SparkQA]

QA tests have started for PR 2645 at commit 167b792.

• This patch merges cleanly.

[SparkQA]

QA tests have finished for PR 2645 at commit b26026f.

• This patch passes unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
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[SparkQA]

QA tests have finished for PR 2645 at commit 167b792.

• This patch passes unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/SparkPullRequestBuilder/21267/Test PASSed.