import maya.OpenMaya as OpenMaya

locA = cmds.spaceLocator()[0]
locB = cmds.spaceLocator()[0]
cmds.setAttr("{}.scaleY".format(locB), -1)

locBMatList = cmds.xform(locB, m=True, ws=True, q=True)
mScrA = OpenMaya.MScriptUtil()
locBMMat =  OpenMaya.MMatrix()
mScrA.createMatrixFromList(locBMatList, locBMMat)

mScrB = OpenMaya.MScriptUtil()
dblPtr = mScrB.asDoublePtr()
mTrsMat = OpenMaya.MTransformationMatrix(locBMMat)
mTrsMat.getScale(dblPtr, OpenMaya.MSpace.kWorld)


mslist = OpenMaya.MSelectionList()
mslist.add("locator1")
mDagPath = OpenMaya.MDagPath()
mslist.getDagPath(0, mDagPath)
loc1MFnTrs = OpenMaya.MFnTransform(mDagPath)
loc1MFnTrs.setScale(dblPtr)
del(dblPtr)