Lint errors in django_bash_completion script

[Albert Wang]

The django_bash_completion script has a few bash lint warnings from shellcheck. None of the errors are likely to affect users, except for using grep -E instead of egrep which should increase compatibility with different systems.

In extras/django_bash_completion line 1:
# #########################################################################
^-- SC2148: Tips depend on target shell and yours is unknown. Add a shebang.


In extras/django_bash_completion line 46:
        echo $PYTHON_EXE | egrep "python([3-9]\.[0-9])?" >/dev/null 2>&1
             ^-- SC2086: Double quote to prevent globbing and word splitting.
                           ^-- SC2196: egrep is non-standard and deprecated. Use grep -E instead.


In extras/django_bash_completion line 47:
        if [[ $? == 0 ]]; then
              ^-- SC2181: Check exit code directly with e.g. 'if mycmd;', not indirectly with $?.


In extras/django_bash_completion line 49:
            echo $PYTHON_SCRIPT | egrep "manage\.py|django-admin(\.py)?" >/dev/null 2>&1
                 ^-- SC2086: Double quote to prevent globbing and word splitting.
                                  ^-- SC2196: egrep is non-standard and deprecated. Use grep -E instead.


In extras/django_bash_completion line 50:
            if [[ $? == 0 ]]; then
                  ^-- SC2181: Check exit code directly with e.g. 'if mycmd;', not indirectly with $?.


In extras/django_bash_completion line 51:
                COMPREPLY=( $( COMP_WORDS="${COMP_WORDS[*]:1}" \
                               ^-- SC2097: This assignment is only seen by the forked process.


In extras/django_bash_completion line 53:
                               DJANGO_AUTO_COMPLETE=1 ${COMP_WORDS[*]} ) )
                                                      ^-- SC2098: This expansion will not see the mentioned assignment.


In extras/django_bash_completion line 67:
    pythons=$(echo $pythons | tr " " "\n" | sort -u | tr "\n" " ")
                   ^-- SC2086: Double quote to prevent globbing and word splitting.

[Albert Wang]

PR at https://code.djangoproject.com/ticket/30283

[Tim Graham <timograham@…>]

In 2ee1e1a:

Fixed #30283 -- Fixed shellcheck warnings in django_bash_completion.