Merge remote-tracking branch 'upstream/master' into interpolate---no-…

…sets-perf

pandas/core/missing.py

@@ -276,30 +276,7 @@ def interpolate_1d(
         result[nans_to_interpolate] = np.interp(
             inds[nans_to_interpolate], inds[valid][indexer], yvalues[valid][indexer]
         )
-        return result
-
-    sp_methods = [
-        "nearest",
-        "zero",
-        "slinear",
-        "quadratic",
-        "cubic",
-        "barycentric",
-        "krogh",
-        "spline",
-        "polynomial",
-        "from_derivatives",
-        "piecewise_polynomial",
-        "pchip",
-        "akima",
-        "cubicspline",
-    ]
-
-    if method in sp_methods:
-        inds = np.asarray(xvalues)
-        # hack for DatetimeIndex, #1646
-        if issubclass(inds.dtype.type, np.datetime64):
-            inds = inds.view(np.int64)
+    else:
         result[nans_to_interpolate] = _interpolate_scipy_wrapper(
             inds[valid],
             yvalues[valid],
@@ -310,7 +287,8 @@ def interpolate_1d(
             order=order,
             **kwargs,
         )
-        return result
+
+    return result
 
 
 def _interpolate_scipy_wrapper(