/usr/lib/emacsen-common/packages/install/elpa-popup is in elpa-popup 0.5.3-1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56  | #!/bin/sh
# /usr/lib/emacsen-common/packages/install/${PACKAGE}
set -e
ELPA_DIR=popup-0.5.3
FLAVOR=$1
case $FLAVOR in
    emacs)
        exit 0
        ;;
    emacs2[0123]*)
        echo install/${ELPA_DIR}: Skipping obsolete emacs ${FLAVOR}
        exit 0
        ;;
    xemacs*)
        echo install/${ELPA_DIR}: Skipping unsupported emacs ${FLAVOR}
        exit 0
        ;;
    *)
        echo install/${ELPA_DIR}: Handling install of emacsen flavor ${FLAVOR}
esac
src_dir=/usr/share/emacs/site-lisp/elpa-src
el_dir=$src_dir/${ELPA_DIR}/
elc_dir=/usr/share/${FLAVOR}/site-lisp/elpa/${ELPA_DIR}/
export EMACSLOADPATH
EMACSLOADPATH="/usr/share/emacs/site-lisp:"
echo install/${ELPA_DIR}: byte-compiling for ${FLAVOR}
[ -d ${elc_dir} ] || mkdir -p ${elc_dir}
# Create symlinks to the .el files (see section 6E in debian-emacs
# polcy).  This makes complation easy, and also allows find-function
# and find-library to work properly.  Also link all other top level
# files and directories into the flavor directory
(cd ${elc_dir} && ln -sf ${el_dir}/* .)
# Byte compile them
(cd ${elc_dir}
 set +e
 ${FLAVOR} -q -batch -l package \
           --eval "(add-to-list 'package-directory-list \"$src_dir\")" \
           -f package-initialize -f batch-byte-compile *.el > Install.log 2>&1
 if test $? -ne 0
 then
   cat Install.log
   exit 1
 fi
 set -e
 gzip -9f Install.log)
exit 0;
 |