fix(build): make `lastUpdated` work with git submodules (#2149)

src/node/markdownToVue.ts

@@ -187,7 +187,7 @@ export async function createMarkdownToVueRenderFn(
     }
 
     if (includeLastUpdatedData) {
-      pageData.lastUpdated = await getGitTimestamp(file)
+      pageData.lastUpdated = await getGitTimestamp(fileOrig)
     }
 
     if (siteConfig?.transformPageData) {

src/node/utils/getGitTimestamp.ts

@@ -1,8 +1,13 @@
 import { spawn } from 'cross-spawn'
+import { basename, dirname } from 'path'
 
 export function getGitTimestamp(file: string) {
   return new Promise<number>((resolve, reject) => {
-    const child = spawn('git', ['log', '-1', '--pretty="%ci"', file])
+    const cwd = dirname(file)
+    const fileName = basename(file)
+    const child = spawn('git', ['log', '-1', '--pretty="%ci"', fileName], {
+      cwd
+    })
     let output = ''
     child.stdout.on('data', (d) => (output += String(d)))
     child.on('close', () => {