Issue #19753: Fix test_gdb on SystemZ buildbot, ignore warnings

--HG--
branch : 2.7
use pythontest.net for url fragment test

--HG--
branch : 2.7
Closes #22525: clarify documentation for ast.literal_eval().

--HG--
branch : 2.7
extra : transplant_source : %5CY%09t%00%26q%A9D%40%00%F6%10%1D%FAM%D2%11%CDy