Fix ANSI escape code wrapping of multi-line deprecation messages

Previously the colourisation of the deprecation messages would break if
the output had prefixes added later (for example as happens when using
an untrusted builder, or when using Git).

Now, each line is wrapped in its own colour code + reset code, which resolves
the issue.

builder-classic-22/end-of-life-buildpack/bin/build

@@ -2,13 +2,20 @@
 
 set -euo pipefail
 
+ANSI_RED="\033[1;31m"
+ANSI_RESET="\033[0m"
+
 function display_error() {
-  local ansi_red="\033[1;31m"
-  local ansi_reset="\033[0m"
-  echo -e "\n${ansi_red}${1}${ansi_reset}\n" >&2
+  echo >&2
+  # We have to ANSI wrap each line separately to prevent breakage if line prefixes are added
+  # later (such as when the builder is untrusted, or when Git adds the "remote:" prefix).
+  while IFS= read -r line; do
+    echo -e "${ANSI_RED}${line}${ANSI_RESET}" >&2
+  done <<< "${1}"
+  echo >&2
 }
 
-read -r -d '' EOL_MESSAGE <<'EOF' || true
+display_error "$(cat <<'EOF'
 #######################################################################
 
 WARNING: This builder image (heroku/builder-classic:22) is deprecated,
@@ -31,6 +38,6 @@ documentation for how to adjust the builder image used for your build.
 
 #######################################################################
 EOF
+)"
 
-display_error "${EOL_MESSAGE}"
 exit 0

buildpacks-20/end-of-life-buildpack/bin/build

@@ -2,13 +2,20 @@
 
 set -euo pipefail
 
+ANSI_RED="\033[1;31m"
+ANSI_RESET="\033[0m"
+
 function display_error() {
-  local ansi_red="\033[1;31m"
-  local ansi_reset="\033[0m"
-  echo -e "\n${ansi_red}${1}${ansi_reset}\n" >&2
+  echo >&2
+  # We have to ANSI wrap each line separately to prevent breakage if line prefixes are added
+  # later (such as when the builder is untrusted, or when Git adds the "remote:" prefix).
+  while IFS= read -r line; do
+    echo -e "${ANSI_RED}${line}${ANSI_RESET}" >&2
+  done <<< "${1}"
+  echo >&2
 }
 
-read -r -d '' EOL_MESSAGE <<'EOF' || true
+display_error "$(cat <<'EOF'
 #######################################################################
 
 WARNING: This builder image (heroku/buildpacks:20) is deprecated,
@@ -31,6 +38,6 @@ documentation for how to adjust the builder image used for your build.
 
 #######################################################################
 EOF
+)"
 
-display_error "${EOL_MESSAGE}"
 exit 0