Update is_sorted.py

[anoubhav]

Changes made-

1. The first 2 return statements have been changed to break statements. This ensures that the code after the first for loop is executed. Previously it would never execute the latter part.
2. The second append statement should add elements to stack and not storage_stack. Try the test case [3,4,7,8,5,6]. The program returns True. It should return False.

(Put an X inside the [ ] to denote check mark [X].)

• If creating a new file :

  • added links to it in the README files ?
  • included tests with it ?
  • added description (overview of algorithm, time and space compleixty, and possible edge case) in docstrings ?

• if done some changes :

  • wrote short description in the PR explaining what the changes do ?
  • Fixes Issue in the code of algorithms/algorithms/stack/is_sorted.py #401 if related to any issue

• other

[coveralls]

Pull Request Test Coverage Report for Build 741

• 3 of 4 (75.0%) changed or added relevant lines in 2 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.06%) to 71.552%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
algorithms/stack/is_sorted.py	2	3	66.67%

Files with Coverage Reduction	New Missed Lines	%
algorithms/search/search_rotate.py	2	92.59%

Totals
Change from base Build 737:	0.06%
Covered Lines:	4306
Relevant Lines:	6018

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💛 - Coveralls

[danghai]

@anoubhav Thanks PR, could you add your test case in test_stack.py in tests too?