Helix fix

[adam-urbanczyk]

Will resolve #271

[codecov]

Codecov Report

Merging #311 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #311   +/-   ##
=======================================
  Coverage   95.26%   95.27%           
=======================================
  Files          18       18           
  Lines        4629     4636    +7     
=======================================
+ Hits         4410     4417    +7     
  Misses        219      219           

Impacted Files	Coverage Δ
cadquery/occ_impl/shapes.py	90.68% <100.00%> (ø)
tests/test_cadquery.py	99.19% <100.00%> (+<0.01%)	⬆️

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[adam-urbanczyk]

Good for merging, simple fix but maybe take a quick look at this @jmwright .

[jmwright]

Looks good, merging. Thanks @adam-urbanczyk