a) For `nixos-rebuild` you can set
  { nixpkgs.config.allowBroken = true; }
in configuration.nix to override this.

b) For `nix-env`, `nix-build`, `nix-shell` or any other Nix command you can add
  { allowBroken = true; }
to ~/.config/nixpkgs/config.nix.

strip is /nix/store/b0zlxla7dmy1iwc3g459rjznx59797xy-binutils-2.28.1/bin/strip
stripping (with command strip and flags -S) in /nix/store/7wnicidgr50vydlih4dcfrn33ncczbzh-mythtv-29.1/lib  /nix/store/7wnicidgr50vydlih4dcfrn33ncczbzh-mythtv-29.1/bin
patching script interpreter paths in /nix/store/7wnicidgr50vydlih4dcfrn33ncczbzh-mythtv-29.1
/nix/store/7wnicidgr50vydlih4dcfrn33ncczbzh-mythtv-29.1/share/mythtv/mythconverg_backup.pl: interpreter directive changed from "/usr/bin/perl -w" to "/nix/store/s029gmjpgvm776wfb56naqny9qja9339-perl-5.24.3/bin/perl -w"
/nix/store/7wnicidgr50vydlih4dcfrn33ncczbzh-mythtv-29.1/share/mythtv/internetcontent/twit.tv.pl: interpreter directive changed from "/usr/bin/env perl" to "/nix/store/s029gmjpgvm776wfb56naqny9qja9339-perl-5.24.3/bin/perl"
/nix/store/7wnicidgr50vydlih4dcfrn33ncczbzh-mythtv-29.1/share/mythtv/internetcontent/topdocumentaryfilm.pl: interpreter directive changed from "/usr/bin/env perl" to "/nix/store/s029gmjpgvm776wfb56naqny9qja9339-perl-5.24.3/bin/perl"
/nix/store/7wnicidgr50vydlih4dcfrn33ncczbzh-mythtv-29.1/share/mythtv/mythconverg_restore.pl: interpreter directive changed from "/usr/bin/perl -w" to "/nix/store/s029gmjpgvm776wfb56naqny9qja9339-perl-5.24.3/bin/perl -w"
checking for references to /tmp/nix-build-mythtv-29.1.drv-0 in /nix/store/7wnicidgr50vydlih4dcfrn33ncczbzh-mythtv-29.1...
postPatchMkspecs
/nix/store/7wnicidgr50vydlih4dcfrn33ncczbzh-mythtv-29.1

make[2]: Circular libavcodec/acelp_filters.o <- libavcodec/ dependency dropped.
CC      libavcodec/acelp_filters.o
make[2]: Circular libavcodec/acelp_pitch_delay.o <- libavcodec/ dependency dropped.
CC      libavcodec/acelp_pitch_delay.o
make[2]: Circular libavcodec/acelp_vectors.o <- libavcodec/ dependency dropped.
CC      libavcodec/acelp_vectors.o
make[2]: Circular libavcodec/adpcm.o <- libavcodec/ dependency dropped.
CC      libavcodec/adpcm.o
building of '/nix/store/f2xsfkw2ncnwkibvn3d0w6qicppcyppm-mythtv-29.1.drv' timed out after 3600 seconds
�[31;1merror:�[0m build of '/nix/store/f2xsfkw2ncnwkibvn3d0w6qicppcyppm-mythtv-29.1.drv' failed