Get the last tag at HEAD~1 for generating release notes

Now that we're relying on a tag push for making releases, the latest tag at HEAD is the release we're currently making, and we want the previous tag.

(in the earlier release process, we generated the release notes *before* creating the tag)

(ignore-relnotes)

PiperOrigin-RevId: 874468315
Change-Id: I1deb413ff6db4803f6c2eaf51da80c287ca78183

Author: hvadehra

.bazelci/presubmit.yml

@@ -95,6 +95,7 @@ tasks:
       - "git commit --allow-empty -m 'Fake init commit'"
       - "git tag -a 'fake-tag-for-testing' -m 'ignore'"
       - "git commit --allow-empty -m 'Fake commit message for testing'"
+      - "git tag -a 'fake-tag-for-testing2' -m 'ignore'"
     test_targets:
       - "//test:check_remote_jdk_configs_test"
       - "//test:check_remote_java_tools_configs_test"

distro/relnotes.bzl

@@ -5,7 +5,7 @@ def print_rel_notes(*, name, version, archive):
         name = name,
         outs = [name + ".txt"],
         cmd = """
-              last_rel=$$(git describe --tags --abbrev=0)
+              last_rel=$$(git describe --tags --abbrev=0 HEAD~1)
               changelog=$$(/usr/bin/git log tags/$$last_rel..HEAD --format=oneline --invert-grep --grep 'ignore-relnotes' --)
               sha=$$(/usr/bin/sha256sum $(SRCS) | cut -d ' '  -f1)
               cat > $@ <<EOF