Revert gh-146402 and update NEWS entry

This reverts commit 8e1469c.

Author: hpkfft

Lib/test/test_cmath.py

@@ -406,8 +406,6 @@ def polar_with_errno_set(z):
                 _testcapi.set_errno(0)
         self.check_polar(polar_with_errno_set)
 
-    @unittest.skipIf(sys.platform.startswith("sunos"),
-                     "skipping, see gh-138573")
     def test_phase(self):
         self.assertAlmostEqual(phase(0), 0.)
         self.assertAlmostEqual(phase(1.), 0.)

Lib/test/test_math.py

@@ -287,8 +287,6 @@ def testAtanh(self):
         self.assertRaises(ValueError, math.atanh, NINF)
         self.assertTrue(math.isnan(math.atanh(NAN)))
 
-    @unittest.skipIf(sys.platform.startswith("sunos"),
-                     "skipping, see gh-138573")
     def testAtan2(self):
         self.assertRaises(TypeError, math.atan2)
         self.ftest('atan2(-1, 0)', math.atan2(-1, 0), -math.pi/2)

Misc/NEWS.d/next/Library/2026-07-20-09-35-32.gh-issue-153144.0a2AoO.rst

@@ -1,7 +1,7 @@
 The return values of ``atan2(0.0, 0.0)``, ``atan2(0.0, -0.0)``, etc. are
-specified in Annex F of the C standard.  The Intel math library, for legacy
-compatibility, also sets ``errno`` to indicate a domain error when both
-arguments are zero.  Python's :func:`math.atan2` and :func:`cmath.phase`
-should return the values specified by Annex F, not raise ``ValueError``.
-This patch fixes these cases when building Python with the Intel math
-library. Contributed by High Performance Kernels LLC.
+specified in Annex F of the C standard.  The Intel and Solaris math libraries,
+for legacy compatibility, also set ``errno`` to indicate a domain error when
+both arguments are zero.  Python's :func:`math.atan2`, :func:`math.atan2pi`,
+and :func:`cmath.phase` should return the values specified by Annex F, not
+raise ``ValueError``.  This patch ignores ``errno`` for the C ``atan2()`` and
+``atan2pi()`` functions.  Contributed by High Performance Kernels LLC.