feat: bail on incompatible git versions

package.json

@@ -57,6 +57,7 @@
     "execa": "^4.0.0",
     "husky": "^4.2.1",
     "lodash": "^4.17.15",
+    "semver": "^7.1.1",
     "toml": "^3.0.0",
     "yargs": "^15.1.0"
   },

src/bin/git-utils.js

@@ -1,3 +1,18 @@
 import execa from 'execa';
+import semver from 'semver';
 
 export const git = (...args) => execa('git', args).then(({ stdout }) => stdout);
+
+async function getGitVersion() {
+  // This produces a string like "git version 2.25.0"
+  const version = await git('version');
+  return version.slice(version.lastIndexOf(' ') + 1);
+}
+
+export async function getCurrentBranch() {
+  if (semver.lt(await getGitVersion(), '2.22.0')) {
+    throw new Error('please upgrade git to at least 2.22.0');
+  }
+
+  return git('branch', '--show-current');
+}

src/bin/hook-commands/pre-push.js

@@ -1,7 +1,7 @@
 import { commitlintOrExit } from '../commitlint';
 import { expectEnabled, getMode } from '../config';
 import { once } from 'lodash';
-import { git } from '../git-utils';
+import { git, getCurrentBranch } from '../git-utils';
 
 const getRemoteBranch = once(async function getRemoteBranch() {
   const headRef = await git('symbolic-ref', '-q', 'HEAD');
@@ -34,7 +34,7 @@ export default {
     switch (mode) {
       case 'unpushed': {
         const [localBranch, remoteBranch] = await Promise.all([
-          git('branch', '--show-current'),
+          getCurrentBranch(),
           getRemoteBranch(),
         ]);