For the record, examples of ignored patterns:

        ignore_patterns = (
            'Function "%s" not defined.' % breakpoint,
            'Do you need "set solib-search-path" or '
            '"set sysroot"?',
            # BFD: /usr/lib/debug/(...): unable to initialize decompress
            # status for section .debug_aranges
            'BFD: ',
            # ignore all warnings
            'warning: ',
            )

Enjoy the older list before I chose to ignore "warning: " :-)

        # Ignore some benign messages on stderr.
        ignore_patterns = (
            'Function "%s" not defined.' % breakpoint,
            "warning: no loadable sections found in added symbol-file"
            " system-supplied DSO",
            "warning: Unable to find libthread_db matching"
            " inferior's thread library, thread debugging will"
            " not be available.",
            "warning: Cannot initialize thread debugging"
            " library: Debugger service failed",
            'warning: Could not load shared library symbols for '
            'linux-vdso.so',
            'warning: Could not load shared library symbols for '
            'linux-gate.so',
            'warning: Could not load shared library symbols for '
            'linux-vdso64.so',
            'Do you need "set solib-search-path" or '
            '"set sysroot"?',
            'warning: Source file is more recent than executable.',
            # Issue #19753: missing symbols on System Z
            'Missing separate debuginfo for ',
            'Try: zypper install -C ',
            )

Oh strange, "Missing separate debuginfo for " message was ignored!

commit f4a4898c18c9cc5ca6d2747789c6586524daf461
Author: Victor Stinner <victor.stinner@gmail.com>
Date:   Sun Nov 24 18:55:25 2013 +0100

    Issue #19753: Try to fix test_gdb on SystemZ buildbot

But I removed it in:

commit 904f5def5cc6da106a1e2e9feb0830cdb1433519
Author: Victor Stinner <victor.stinner@gmail.com>
Date:   Wed Mar 23 18:32:54 2016 +0100

    Try to fix test_gdb on s390x buildbots