fix(tests): scrub GIT_* env vars leaking from the pre-commit hook into git-fixture tests

server/lib/update-check.js's execGit() and two test helpers
(lanes-cli.test.js, update-check.test.js) shelled out to git with an
explicit `cwd` but no `env` override. A parent git hook process (this
repo's own .husky/pre-commit, which runs `npm run test:server`) sets
GIT_DIR/GIT_INDEX_FILE in its own environment; those leak to every
child process and take precedence over `cwd` for repo discovery, so
every git command these tests ran against their throwaway tmp repos
was silently redirected at the real repo running the hook instead —
reproduced firsthand as four foreign "init"/"fixture" commits
overwriting a worktree branch mid pre-commit run. Fixes it the same
way server/lib/worktree.js already documented and did for its own git
calls: strip the GIT_* vars before exec.

server/__tests__/update-check.test.js

@@ -14,11 +14,28 @@ const { execFileSync } = require("child_process");
 
 const { getUpdatesStatus } = require("../lib/update-check");
 
+// Strip GIT_* vars a parent git hook (e.g. the pre-commit hook running this
+// very suite) sets in its own environment — those leak to every child
+// process and override an explicit `cwd`, so without this a git command
+// meant for this test's throwaway tmp repo silently operates on the real
+// repo running the hook instead.
+const GIT_ENV = { ...process.env };
+delete GIT_ENV.GIT_DIR;
+delete GIT_ENV.GIT_WORK_TREE;
+delete GIT_ENV.GIT_INDEX_FILE;
+delete GIT_ENV.GIT_COMMON_DIR;
+delete GIT_ENV.GIT_OBJECT_DIRECTORY;
+delete GIT_ENV.GIT_ALTERNATE_OBJECT_DIRECTORIES;
+delete GIT_ENV.GIT_PREFIX;
+delete GIT_ENV.GIT_NAMESPACE;
+delete GIT_ENV.GIT_CONFIG_PARAMETERS;
+
 function git(cwd, args) {
   return execFileSync("git", args, {
     cwd,
     stdio: ["ignore", "pipe", "pipe"],
     encoding: "utf8",
+    env: GIT_ENV,
   }).trim();
 }
 
@@ -29,6 +46,7 @@ function makeBareRemote(parent, name) {
   // i.e. far older than --initial-branch.
   execFileSync("git", ["-c", "init.defaultBranch=master", "init", "--bare", repo], {
     stdio: "ignore",
+    env: GIT_ENV,
   });
   return repo;
 }
@@ -36,7 +54,10 @@ function makeBareRemote(parent, name) {
 function makeWorkingRepo(parent, dir, originUrl) {
   const repo = path.join(parent, dir);
   fs.mkdirSync(repo, { recursive: true });
-  execFileSync("git", ["-c", "init.defaultBranch=master", "init", repo], { stdio: "ignore" });
+  execFileSync("git", ["-c", "init.defaultBranch=master", "init", repo], {
+    stdio: "ignore",
+    env: GIT_ENV,
+  });
   fs.writeFileSync(path.join(repo, "README.md"), "fixture\n");
   git(repo, ["-c", "user.email=t@t", "-c", "user.name=t", "add", "."]);
   git(repo, ["-c", "user.email=t@t", "-c", "user.name=t", "commit", "-m", "init"]);
@@ -146,7 +167,10 @@ describe("getUpdatesStatus — no remotes configured", () => {
   it("returns a soft no-remotes payload", async () => {
     const repo = path.join(tmpDir, "noremote");
     fs.mkdirSync(repo, { recursive: true });
-    execFileSync("git", ["-c", "init.defaultBranch=master", "init", repo], { stdio: "ignore" });
+    execFileSync("git", ["-c", "init.defaultBranch=master", "init", repo], {
+      stdio: "ignore",
+      env: GIT_ENV,
+    });
     fs.writeFileSync(path.join(repo, "README.md"), "lonely\n");
     git(repo, ["-c", "user.email=t@t", "-c", "user.name=t", "add", "."]);
     git(repo, ["-c", "user.email=t@t", "-c", "user.name=t", "commit", "-m", "init"]);