packagekit: link issue references in Markdown changelogs

Markdown changelogs are rendered with markdown-to-jsx, so issue
references in them were not linked like in plain-text changelogs. Use
a renderRule to run text nodes through renderChangelogWithIssueLinks(),
skipping text that is already inside a Markdown link or an <a> tag.

state.inAnchor is only set while parsing, not while rendering, so track
link nesting ourselves: a link's children are rendered inside its
next() call.

Add a Markdown entry to the mock updates for manual testing.

pkg/packagekit/mock-updates.js

@@ -127,4 +127,16 @@ export function injectMockUpdates(updates) {
         severity: 4,
         description: "Fixes rhbz#12345 and RHEL-67890 in one update.",
     });
+
+    // Markdown changelog: plain references get linked, existing links are kept as they are
+    updates.push({
+        id: "tracker-links-markdown;1-1",
+        name: "tracker-links-markdown",
+        version: "1-1",
+        bug_urls: [],
+        cve_urls: [],
+        severity: 4,
+        description: "Fixes rhbz#12345 and *RHEL-67890*\n\n * already linked: [RHEL-11111](https://redhat.atlassian.net/browse/RHEL-11111)\n * not a reference: `RHEL-22222`",
+        markdown: true,
+    });
 }

pkg/packagekit/updates.jsx

@@ -41,7 +41,7 @@ import {
     SecurityIcon,
 } from "@patternfly/react-icons";
 import { TableText } from "@patternfly/react-table";
-import Markdown from "markdown-to-jsx";
+import Markdown, { RuleType } from "markdown-to-jsx";
 
 import { AutoUpdates, getBackend } from "./autoupdates.jsx";
 import { KpatchSettings, KpatchStatus } from "./kpatch";
@@ -473,6 +473,30 @@ function isSafeUrl(href) {
     }
 }
 
+// Link issue references in Markdown text, except for text that is already part of a link.
+// markdown-to-jsx renders a node's children inside its next() call, so track link nesting
+// here; state.inAnchor is only set while parsing, not while rendering.
+let markdownLinkDepth = 0;
+
+function renderMarkdownWithIssueLinks(next, node, _renderChildren, state) {
+    if (node.type === RuleType.link || (node.type === RuleType.htmlBlock && node.tag === "a")) {
+        markdownLinkDepth++;
+        try {
+            return next();
+        } finally {
+            markdownLinkDepth--;
+        }
+    }
+
+    if (node.type === RuleType.text && markdownLinkDepth === 0) {
+        const linked = renderChangelogWithIssueLinks(node.text);
+        if (linked !== node.text)
+            return <React.Fragment key={state.key}>{linked}</React.Fragment>;
+    }
+
+    return next();
+}
+
 const markdownOptions = {
     overrides: {
         a: {
@@ -483,6 +507,7 @@ const markdownOptions = {
         },
     },
     forceInline: true,
+    renderRule: renderMarkdownWithIssueLinks,
 };
 
 function updateItem(info, pkgNames, key, partialUpdates) {