BUG: Fixed 19497 - previously, renaming an index changed its type if …

[charlie0389]

Fixes bug GH19497 - previously, renaming an index with tuples changed its type (i.e. from Index to MultiIndex).

• closes Bug: rename incapable of accepting tuples as new name #19497
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff

[codecov]

Codecov Report

Merging #21029 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #21029      +/-   ##
==========================================
- Coverage   91.82%   91.82%   -0.01%     
==========================================
  Files         153      153              
  Lines       49502    49502              
==========================================
- Hits        45457    45455       -2     
- Misses       4045     4047       +2

Flag	Coverage Δ
#multiple	90.22% <100%> (-0.01%)	⬇️
#single	41.88% <100%> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/core/internals.py	95.59% <100%> (ø)	⬆️
pandas/util/testing.py	84.38% <0%> (-0.21%)	⬇️
pandas/io/parsers.py	95.46% <0%> (ø)	⬆️

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[jreback]

ok, lgtm. can you add a note in bug fixes / indexing section. ping on green.

[TomAugspurger]

Added whatsnew.

[jreback]

thanks @charlie0389

[charlie0389]

My pleasure :)