Stop filtering out pip's "Requirement already satisfied" lines

Since while removing them makes the install logs slightly shorter,
it hides what is happening and makes it harder to see what package
version a historic build may have been using from the logs alone.
For example, when comparing a last successful build to a newly
failing build.

This now matches the behaviour for our other supported package
managers, where we don't filter out install lines relating to already
installed/cached packages.

As a compromise, we still edit the lines slightly, to remove the redundant
site-packages path information, which would otherwise cause each
package message to span multiple lines.

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## [Unreleased]
 
+- Stopped filtering out pip's `Requirement already satisfied:` lines when installing dependencies. ([#1765](https://github.com/heroku/heroku-buildpack-python/pull/1765))
 - Improved the error messages shown if installing pip/Poetry/Pipenv fails. ([#1764](https://github.com/heroku/heroku-buildpack-python/pull/1764))
 - Stopped installing pip into Poetry's virtual environment. ([#1761](https://github.com/heroku/heroku-buildpack-python/pull/1761))
 

lib/pip.sh

@@ -106,6 +106,8 @@ function pip::install_dependencies() {
 	# We only display the most relevant command args here, to improve the signal to noise ratio.
 	output::step "Installing dependencies using '${pip_install_command[*]}'"
 
+	# The sed usage is to reduce the verbosity of output lines like:
+	# "Requirement already satisfied: typing-extensions==4.12.2 in /app/.heroku/python/lib/python3.13/site-packages (from -r requirements.txt (line 5)) (4.12.2)"
 	# shellcheck disable=SC2310 # This function is invoked in an 'if' condition so set -e will be disabled.
 	if ! {
 		"${pip_install_command[@]}" \
@@ -116,7 +118,7 @@ function pip::install_dependencies() {
 			--progress-bar off \
 			--src='/app/.heroku/python/src' \
 			|& tee "${WARNINGS_LOG:?}" \
-			|& sed --unbuffered --expression '/Requirement already satisfied/d' \
+			|& sed --unbuffered --expression 's# in /app/.heroku/python/lib/python.*/site-packages##' \
 			|& output::indent
 	}; then
 		# TODO: Overhaul warnings and combine them with error handling.

spec/hatchet/ci_spec.rb

@@ -62,16 +62,19 @@
         REGEX
 
         test_run.run_again
-        expect(clean_output(test_run.output)).to include(<<~OUTPUT)
+        expect(clean_output(test_run.output)).to match(Regexp.new(<<~REGEX, Regexp::MULTILINE))
           -----> Python app detected
           -----> Using Python #{DEFAULT_PYTHON_MAJOR_VERSION} specified in .python-version
           -----> Restoring cache
           -----> Using cached install of Python #{DEFAULT_PYTHON_FULL_VERSION}
           -----> Installing pip #{PIP_VERSION}
           -----> Installing dependencies using 'pip install -r requirements.txt -r requirements-test.txt'
+                 Requirement already satisfied: typing-extensions==.+
+                 Requirement already satisfied: pytest==.+
+                 .+
           -----> Skipping Django collectstatic since the env var DISABLE_COLLECTSTATIC is set.
           -----> Running bin/post_compile hook
-        OUTPUT
+        REGEX
       end
     end
   end

spec/hatchet/pip_spec.rb

@@ -53,6 +53,7 @@
           remote: -----> Using cached install of Python #{DEFAULT_PYTHON_FULL_VERSION}
           remote: -----> Installing pip #{PIP_VERSION}
           remote: -----> Installing dependencies using 'pip install -r requirements.txt'
+          remote:        Requirement already satisfied: typing-extensions==4.12.2 (from -r requirements.txt (line 5)) (4.12.2)
           remote: -----> Inline app detected
         OUTPUT
       end