Following-up sbaird's comment, I must point out that those aren't Python-specific results. Filtering them by appending &l=python to the urls yields:
- "TAU = 2 * Math.PI": 6
- "TAU = 2*Math.PI": 2
- "TAU=2*Math.PI": 0
- "TAU = Math.PI * 2": 0
- "TAU = Math.PI*2": 2
- "TAU=Math.PI*2": 1
(total: 11)

- "TAU = 2 * PI": 9
- "TAU = 2*PI": 12
- "TAU=2*PI": 0
- "TAU = PI * 2": 2
- "TAU = PI*2": 0
- "TAU=PI*2": 0
(total: 23)

Then again, the results for all languages are still helpful to estimate the overall adoption of the notation in code, and indeed the global usage of these patterns (in github only) is in the hundreds.

Also, it's worth taking a look at the usage of the twopi constant, which is already defined in several languages (http://en.wikipedia.org/w/index.php?oldid=509096802#Support_in_programming_languages), and has been manually defined in python quite often, proving its usefulness:

- https://github.com/search?l=python&q=twopi&type=Code (~2k results in python, and ~58k overall)
- https://github.com/search?l=python&q=two_pi&type=Code (~200 results in python, ~23k overall)