/usr/share/doc/cpp-mips64-linux-gnuabi64/README.Bugs is in gcc-mips64-linux-gnuabi64 4:7.3.0-3ubuntu1.
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It is a symlink to /usr/share/doc/cpp-mips64-linux-gnuabi64/../gcc-7-mips64-linux-gnuabi64-base/README.Bugs