Failing builds on Travis

Hi, The success of builds on Travis seems to hinge on a particular test case: ext/standard/tests/file/disk_free_space_basic.phpt It asserts that if a file is written to, the free space after the write must always be lower than the previously recorded value. On a busy system the free space is affected by many factors that can cause this assertion to fail and thus developers get a nasty looking (X) on their pull requests. Can't we just assert that "the function returns a float, hurray!" instead? -- -- Tjerk