Description:
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PHP5.6 handled the same way file names without extension written either "filename" or "filename." (with dot character at the end of the file name).

PHP7.1.3 handles both forms of file name only in some of the functions but throws warning "Permission denied" in others.

OK functions: file_get_contents, file_exists

Bad functions: file_put_contents, copy, rename


Test script:
---------------
1) 

file_put_contents('test.', 'test.');

2)

file_put_contents('test.txt', 'test.txt');
copy('test.txt', 'test.');

3)

file_put_contents('test.txt', 'test.txt');
rename('test.txt', 'test.');

Expected result:
----------------
1) File "test" written to file system with "test." content.

2) File "test" exists in file system with "test.txt" content.

3) File "test" exists in file system with "test.txt" content.


Actual result:
--------------
1-3) Warning: Permission denied.

Files not created.