TST: adding test cases for COO sum_duplicates
ENH: adding sum_duplicates method to COO matrix
adding has_canonical_format to COO matrix
fixing build errors
incorporating @jaimefrio's vectorized version
MAINT: attempt to improve svds of singular matrices, passes existing tests
MAINT: sparse svd passes new tests
MAINT: simplify code and tests for sparse singular svd
monic is a boolean parameter: False instead of 0
use True/False for boolean `mu` arguments
STY: autopep8 and some manual cleanup

but didn't modify some ugly lambdas
DOC: expand scipy.special.legendre docstring

(I think n must be int, but not sure.)
FIX incorrect sorting during fancy assignment

Bug reported by @perimosocordiae on #3264
BUG: fixing linprog's kwarg order to match docs

The upper bound and equality constraint kwargs were swapped, which means that people following the docstring ordering (and not using keywords) would inadvertently supply the wrong constraints.
Merge pull request #3886 from perimosocordiae/patch-6

BUG: fixing linprog's kwarg order to match docs
BUG: Handle the case where status != 2

The local variable `message` wasn't being set in all cases, causing runtime errors.
Merge pull request #3888 from perimosocordiae/patch-6

BUG: optimize: In _linprog_simplex, handle the case where the status returned by _solve_simplex is not 0 or 2.
DOC: sparse.linalg: Fix lobpcg docstring.

Change the markup of the "Acknowledgements" title from a section heading
to emphasis markers within the "Notes" section.

The docstring standard doesn't include an "Acknowledgements" section,
so including one in a docstring generates a warning when building the
docs, and the section is not included in the HTML output.
Merge pull request #3892 from WarrenWeckesser/doc-lobpcg

DOC: sparse.linalg: Fix lobpcg docstring.
DOC: stats: Remove the trailing '_' from the reference to 'levene'.