Get bash-5.1.16.tar.gz from https://ftp.gnu.org/gnu/bash/.
Gunzip it. Extract the original: tar xf bash-5.1.16.tar && mv bash-5.1.16 bash-org. Remove lib/glob from bash-org: rm -r bash-org/lib/glob. Now delete lib/glob from the tar file using: tar --delete --no-recursion --no-wildcards -f 'bash-5.1.16.tar' -- 'bash-5.1.16/lib/glob/sm_loop.c' 'bash-5.1.16/lib/glob/glob.h' 'bash-5.1.16/lib/glob/xmbsrtowcs.c' 'bash-5.1.16/lib/glob/glob.c' 'bash-5.1.16/lib/glob/smatch.c' 'bash-5.1.16/lib/glob/doc/glob.texi' 'bash-5.1.16/lib/glob/doc/Makefile' 'bash-5.1.16/lib/glob/doc/' 'bash-5.1.16/lib/glob/gm_loop.c' 'bash-5.1.16/lib/glob/Makefile.in' 'bash-5.1.16/lib/glob/gmisc.c' 'bash-5.1.16/lib/glob/collsyms.h' 'bash-5.1.16/lib/glob/glob_loop.c' 'bash-5.1.16/lib/glob/strmatch.c' 'bash-5.1.16/lib/glob/ndir.h' 'bash-5.1.16/lib/glob/strmatch.h' 'bash-5.1.16/lib/glob/'. Extract the changed tar file: tar xf bash-5.1.16.tar && mv bash-5.1.16 bash-del. Now compare: diff -Nur bash-org bash-del. You'll find lib/readline/doc/hstech.texi changed and lib/readline/doc/rluserman.texi deleted! This happens with tar 1.30 (debian/buster) as well as with tar 1.34 (self-compiled).
