fix: handle actions/checkout v6 credential storage change (#6667)

packages/opencode/src/cli/cmd/github.ts

@@ -994,12 +994,16 @@ export const GithubRunCommand = cmd({
 
         console.log("Configuring git...")
         const config = "http.https://github.com/.extraheader"
-        const ret = await $`git config --local --get ${config}`
-        gitConfig = ret.stdout.toString().trim()
+        // actions/checkout@v6 no longer stores credentials in .git/config,
+        // so this may not exist - use nothrow() to handle gracefully
+        const ret = await $`git config --local --get ${config}`.nothrow()
+        if (ret.exitCode === 0) {
+          gitConfig = ret.stdout.toString().trim()
+          await $`git config --local --unset-all ${config}`
+        }
 
         const newCredentials = Buffer.from(`x-access-token:${appToken}`, "utf8").toString("base64")
 
-        await $`git config --local --unset-all ${config}`
         await $`git config --local ${config} "AUTHORIZATION: basic ${newCredentials}"`
         await $`git config --global user.name "${AGENT_USERNAME}"`
         await $`git config --global user.email "${AGENT_USERNAME}@users.noreply.github.com"`