Add {% load i18n %} to templates which are missing it

add-missing-load-i18n.sh

# Add {% load i18n %} to templates which are missing it
#
# How this works?
# Step 1: Find all files in templates folder
# Step 2: Print file name of that file if file has at least one trans or blocktrans tag
# Step 3: Put load tag on the first or second line, depending if the first line is extends tag
#
# Elaborate on the third step:
#
# 1 { # Operate only on the first line
#   # If the first line is extends tag
#   /^{% extends/ {
#     p # Dump it immediately to output
#     x # And replace it by empty line (actually hides into another buffer)
#   }
#   # Insert the line with the tag
#   # (text for command i ends by new line character;
#   # in a one liner we can split it using -e parameter)
#   i{% load i18n %}
#   # If the first line was extends tag, we have empty line in buffer, delete it
#   /^$/d
#  }

find templates/ -type f -exec \
    awk '/{% load i18n %}/ { ++l } /{% trans|{% blocktrans/ {++t} END { if (t && !l) print FILENAME}' \
    {} \; | xargs \
    sed -i -e '1{/^{% extends/ {p;x}; i{% load i18n %}' -e '/^$/d}'