pip-tools: [Windows] FileExistsError using pip-compile

Using pip-compile requirements.in --output-file=requirements.txt fails at overriding if the output-file already exists (using Windows, OS X works fine).

Steps to replicate

1. pip-compile requirements.in --output-file=requirements.txt (when requirements.txt doesn’t exist)
2. run the command above again (requirements.txt now exists)

Expected result (by step)

1. create requirements.txt
2. override existing requirements.txt

Actual result (by step)

1. works fine

2. following error is raised (in German):

   FileExistsError: [WinError 183] Eine Datei kann nicht erstellt werden, wenn sie bereits vorhanden ist: 'requirements.txt.part' -> 'C:\\Users\\floqqi\\Projects\\test\\requirements.txt'
   

   which roughly translates to Can not create file, if it is already existing: 'requirements.txt.part' -> ...