Fix bug, only add tarball when git installed

[dachengx]

Otherwise, you will see error like:

Traceback (most recent call last):
  File "/home/xudc/alea/alea/scripts/alea_submission.py", line 99, in <module>
    main()
  File "/home/xudc/alea/alea/scripts/alea_submission.py", line 95, in main
    submitter.submit()
  File "/home/xudc/alea/alea/submitters/htcondor.py", line 700, in submit
    self._generate_workflow()
  File "/home/xudc/alea/alea/submitters/htcondor.py", line 585, in _generate_workflow
    job.add_inputs(
  File "/usr/lib64/pegasus/python/Pegasus/api/_utils.py", line 85, in wrapper
    assert f(self, *args, **kwargs) == None
  File "/usr/lib64/pegasus/python/Pegasus/api/workflow.py", line 88, in add_inputs
    raise DuplicateError(
Pegasus.api.errors.DuplicateError: file: alea.tar.gz has already been added as input to this job

[coveralls]

Pull Request Test Coverage Report for Build 11964278524

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.1%) to 89.748%

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Totals
Change from base Build 11815730221:	0.1%
Covered Lines:	1707
Relevant Lines:	1902

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💛 - Coveralls