Ensure nested ordered identifiers are grouped (fixes #745)

[john-bodley]

Fixes #745.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (f101546) 96.97% compared to head (d43fb9c) 96.98%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #746   +/-   ##
=======================================
  Coverage   96.97%   96.98%           
=======================================
  Files          20       20           
  Lines        1556     1557    +1     
=======================================
+ Hits         1509     1510    +1     
  Misses         47       47           

Files	Coverage Δ
sqlparse/engine/grouping.py	100.00% <100.00%> (ø)

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[andialbrecht]

Ah, cool! Thanks for finding this!