Python uninstall kills link to Python directory

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Python

(Am I blind, or is there no Code Project Python forum? Can't fnd any!)

When I uninstall certain python packages using pip uninstall, notably nose and ipython, the link to the Python directory (such as C:\Python27 for version 2.7.9 or C:\Python34 for version 3.4.2) goes with it. Lots of scripts and code refer to Python through these links, and fail. Until I have restored the link, for all practical purposes Python is not accessible.

Can anyone explain why this happens, and if possible, how to avoid it?

The problem is the same under Windows 7 and Windows 10 (both 64 bits), with nose 1.3.4 and 1.3.7, on several dozen mahcines of various age and configuration, under Python 2.7.9 and Python 3.4.2 (both 32 bits). This applies to a couple packages only, all other (100+) packages install and uninstall without such problems.

The C:\Python link is not deleted, only the version specific one.

What I have tried:

Different Windows versions (7, 10).
Different Python versions (2.7.9, 3.4.2).
Different machines (several dozen different ones).
Different package versions (nose 1.3.4, 1.3.7).