Using context overrides in Python caused problems for any operator that changed the context and require these changes to be read back. CTX_wm_area_set() for e.g. would set the struct member but future calls to CTX_wm_area() would still return the value defined by Python callers context overrides. This also resolves a mismatch between polling and calling operators from Python, where poll would override the Python context where calling only overrode the context when a new context was passed in.