REF: move IntervalIndex.equals up to ExtensionIndex.equals

[jbrockmendel]

No description provided.

[jreback]

any more equals you can remove because of this? (followon)

[jbrockmendel]

any more equals you can remove because of this? (followon)

Not without API changes, but it may be worthwhile to get these more strict/consistent

[jbrockmendel]

any more equals you can remove because of this? (followon)

Not without API changes, but it may be worthwhile to get these more strict/consistent

So the least invasive would be CategoricalIndex. Changing it to match this strict version (actually just removing it) breaks 5 tests. Four of these are asserting index.equals(index.astype(object)), which we test for all Index subclasses except IntervalIndex (which suggests IntervalIndex possibly should support this)

The fifth is an indexing test that may indicate a bug elsewhere:

        df = DataFrame(np.random.randn(3, 3), index=list("ABA"), columns=list("XYX"))
        cdf = df.copy()
        cdf.index = CategoricalIndex(df.index)
        cdf.columns = CategoricalIndex(df.columns)
    
        exp_index = CategoricalIndex(list("AA"), categories=["A", "B"])
>       expect = DataFrame(df.loc["A", :], columns=cdf.columns, index=exp_index)
[...]
E           ValueError: cannot reindex from a duplicate axis