Start a env_parallel session to avoid argument too long errors (#1446)

Co-authored-by: Gulshan Singh <gsgx@google.com>
Fixes https://github.com/pwndbg/pwndbg/issues/1430

tests/gdb-tests/tests.sh

@@ -3,6 +3,19 @@
 set -o errexit
 set -o pipefail
 
+# env_parallel will fail if there are too many environment variables, so we need
+# to use `--session` or `--record-env`, and only `--record-env` is supported on
+# the version of `parallel` on Ubuntu 20.04 and earlier. The directory also
+# needs to be created for CI
+mkdir -p ~/.parallel
+. $(which env_parallel.bash)
+
+# Workaround for Ubuntu 20.04/18.04 CI. If no aliases are defined
+# `env_parallel --record-env` will have non-zero exit code for older versions of
+# `parallel`, so we define a dummy alias here
+alias __dummy=foo
+env_parallel --record-env
+
 ROOT_DIR="$(readlink -f ../../)"
 GDB_INIT_PATH="$ROOT_DIR/gdbinit.py"
 COVERAGERC_PATH="$ROOT_DIR/pyproject.toml"
@@ -167,9 +180,8 @@ else
         echo ""
     fi
 
-    . $(which env_parallel.bash)
-
-    env_parallel --output-as-files --joblog $JOBLOG_PATH run_test ::: "${TESTS_LIST[@]}" | env_parallel parse_output_file {}
+    # The `--env _` is required when using `--record-env`
+    env_parallel --env _ --output-as-files --joblog $JOBLOG_PATH run_test ::: "${TESTS_LIST[@]}" | env_parallel --env _ parse_output_file {}
 fi
 
 end=$(date +%s)