Merge branch 'ds/decorate-filter-tweak'

The namespaces used by "log --decorate" from "refs/" hierarchy by
default has been tightened.

* ds/decorate-filter-tweak:
  fetch: use ref_namespaces during prefetch
  maintenance: stop writing log.excludeDecoration
  log: create log.initialDecorationSet=all
  log: add --clear-decorations option
  log: add default decoration filter
  log-tree: use ref_namespaces instead of if/else-if
  refs: use ref_namespaces for replace refs base
  refs: add array of ref namespaces
  t4207: test coloring of grafted decorations
  t4207: modernize test
  refs: allow "HEAD" as decoration filter

t/t4202-log.sh

@@ -704,9 +704,12 @@ test_expect_success 'set up more tangled history' '
 	git checkout -b tangle HEAD~6 &&
 	test_commit tangle-a tangle-a a &&
 	git merge main~3 &&
+	git update-ref refs/prefetch/merge HEAD &&
 	git merge side~1 &&
+	git update-ref refs/rewritten/merge HEAD &&
 	git checkout main &&
 	git merge tangle &&
+	git update-ref refs/hidden/tangle HEAD &&
 	git checkout -b reach &&
 	test_commit reach &&
 	git checkout main &&
@@ -974,9 +977,9 @@ test_expect_success 'decorate-refs-exclude and simplify-by-decoration' '
 	Merge-tag-reach (HEAD -> main)
 	reach (tag: reach, reach)
 	seventh (tag: seventh)
-	Merge-branch-tangle
-	Merge-branch-side-early-part-into-tangle (tangle)
-	tangle-a (tag: tangle-a)
+	Merge-branch-tangle (refs/hidden/tangle)
+	Merge-branch-side-early-part-into-tangle (refs/rewritten/merge, tangle)
+	Merge-branch-main-early-part-into-tangle (refs/prefetch/merge)
 	EOF
 	git log -n6 --decorate=short --pretty="tformat:%f%d" \
 		--decorate-refs-exclude="*octopus*" \
@@ -1025,6 +1028,115 @@ test_expect_success 'decorate-refs and simplify-by-decoration without output' '
 	test_cmp expect actual
 '
 
+test_expect_success 'decorate-refs-exclude HEAD' '
+	git log --decorate=full --oneline \
+		--decorate-refs-exclude="HEAD" >actual &&
+	! grep HEAD actual
+'
+
+test_expect_success 'decorate-refs focus from default' '
+	git log --decorate=full --oneline \
+		--decorate-refs="refs/heads" >actual &&
+	! grep HEAD actual
+'
+
+test_expect_success '--clear-decorations overrides defaults' '
+	cat >expect.default <<-\EOF &&
+	Merge-tag-reach (HEAD -> refs/heads/main)
+	Merge-tags-octopus-a-and-octopus-b
+	seventh (tag: refs/tags/seventh)
+	octopus-b (tag: refs/tags/octopus-b, refs/heads/octopus-b)
+	octopus-a (tag: refs/tags/octopus-a, refs/heads/octopus-a)
+	reach (tag: refs/tags/reach, refs/heads/reach)
+	Merge-branch-tangle
+	Merge-branch-side-early-part-into-tangle (refs/heads/tangle)
+	Merge-branch-main-early-part-into-tangle
+	tangle-a (tag: refs/tags/tangle-a)
+	Merge-branch-side
+	side-2 (tag: refs/tags/side-2, refs/heads/side)
+	side-1 (tag: refs/tags/side-1)
+	Second
+	sixth
+	fifth
+	fourth
+	third
+	second
+	initial
+	EOF
+	git log --decorate=full --pretty="tformat:%f%d" >actual &&
+	test_cmp expect.default actual &&
+
+	cat >expect.all <<-\EOF &&
+	Merge-tag-reach (HEAD -> refs/heads/main)
+	Merge-tags-octopus-a-and-octopus-b
+	seventh (tag: refs/tags/seventh)
+	octopus-b (tag: refs/tags/octopus-b, refs/heads/octopus-b)
+	octopus-a (tag: refs/tags/octopus-a, refs/heads/octopus-a)
+	reach (tag: refs/tags/reach, refs/heads/reach)
+	Merge-branch-tangle (refs/hidden/tangle)
+	Merge-branch-side-early-part-into-tangle (refs/rewritten/merge, refs/heads/tangle)
+	Merge-branch-main-early-part-into-tangle (refs/prefetch/merge)
+	tangle-a (tag: refs/tags/tangle-a)
+	Merge-branch-side
+	side-2 (tag: refs/tags/side-2, refs/heads/side)
+	side-1 (tag: refs/tags/side-1)
+	Second
+	sixth
+	fifth
+	fourth
+	third
+	second
+	initial
+	EOF
+	git log --decorate=full --pretty="tformat:%f%d" \
+		--clear-decorations >actual &&
+	test_cmp expect.all actual &&
+	git -c log.initialDecorationSet=all log \
+		--decorate=full --pretty="tformat:%f%d" >actual &&
+	test_cmp expect.all actual
+'
+
+test_expect_success '--clear-decorations clears previous exclusions' '
+	cat >expect.all <<-\EOF &&
+	Merge-tag-reach (HEAD -> refs/heads/main)
+	reach (tag: refs/tags/reach, refs/heads/reach)
+	Merge-tags-octopus-a-and-octopus-b
+	octopus-b (tag: refs/tags/octopus-b, refs/heads/octopus-b)
+	octopus-a (tag: refs/tags/octopus-a, refs/heads/octopus-a)
+	seventh (tag: refs/tags/seventh)
+	Merge-branch-tangle (refs/hidden/tangle)
+	Merge-branch-side-early-part-into-tangle (refs/rewritten/merge, refs/heads/tangle)
+	Merge-branch-main-early-part-into-tangle (refs/prefetch/merge)
+	tangle-a (tag: refs/tags/tangle-a)
+	side-2 (tag: refs/tags/side-2, refs/heads/side)
+	side-1 (tag: refs/tags/side-1)
+	initial
+	EOF
+
+	git log --decorate=full --pretty="tformat:%f%d" \
+		--simplify-by-decoration \
+		--decorate-refs-exclude="heads/octopus*" \
+		--decorate-refs="heads" \
+		--clear-decorations >actual &&
+	test_cmp expect.all actual &&
+
+	cat >expect.filtered <<-\EOF &&
+	Merge-tags-octopus-a-and-octopus-b
+	octopus-b (refs/heads/octopus-b)
+	octopus-a (refs/heads/octopus-a)
+	initial
+	EOF
+
+	git log --decorate=full --pretty="tformat:%f%d" \
+		--simplify-by-decoration \
+		--decorate-refs-exclude="heads/octopus" \
+		--decorate-refs="heads" \
+		--clear-decorations \
+		--decorate-refs-exclude="tags/" \
+		--decorate-refs="heads/octopus*" >actual &&
+	test_cmp expect.filtered actual
+'
+
 test_expect_success 'log.decorate config parsing' '
 	git log --oneline --decorate=full >expect.full &&
 	git log --oneline --decorate=short >expect.short &&
@@ -2192,6 +2304,20 @@ test_expect_success 'log --decorate includes all levels of tag annotated tags' '
 	test_cmp expect actual
 '
 
+test_expect_success 'log --decorate does not include things outside filter' '
+	reflist="refs/prefetch refs/rebase-merge refs/bundle" &&
+
+	for ref in $reflist
+	do
+		git update-ref $ref/fake HEAD || return 1
+	done &&
+
+	git log --decorate=full --oneline >actual &&
+
+	# None of the refs are visible:
+	! grep /fake actual
+'
+
 test_expect_success 'log --end-of-options' '
        git update-ref refs/heads/--source HEAD &&
        git log --end-of-options --source >actual &&