Desktop: Improved: Show git branch and hash in About dialog (#1692)

* show git branch and hash in About dialog

This additional info will only be shown, if the code is not an official release.

An official release is calculated as follows:
- current commit has a tag
- the tag contains the version number of the package

However, the information will always be printed to the console.

* info will now always be shown in About dialog (if available)

ElectronClient/app/compile-package-info.js: added warning
ElectronClient/app/app.js: push info conditionally to the message array

* use sprintf syntax

ElectronClient/app/app.js

@@ -512,12 +512,20 @@ class Application extends BaseApplication {
 
 		function _showAbout() {
 			const p = packageInfo;
+			let gitInfo = '';
+			if ("git" in p) {
+				gitInfo = _('Revision: %s (%s)', p.git.hash, p.git.branch);
+			}
 			let message = [
 				p.description,
 				'',
 				'Copyright © 2016-2019 Laurent Cozic',
 				_('%s %s (%s, %s)', p.name, p.version, Setting.value('env'), process.platform),
 			];
+			if (!!gitInfo) {
+				message.push("\n" + gitInfo);
+				console.info(gitInfo);
+			}
 			bridge().showInfoMessageBox(message.join('\n'), {
 				icon: bridge().electronApp().buildDir() + '/icons/32x32.png',
 			});

ElectronClient/app/compile-package-info.js

@@ -1,4 +1,5 @@
 const fs = require('fs-extra');
+const execSync = require('child_process').execSync;
 
 // Electron Builder strip off certain important keys from package.json, which we need, in particular build.appId
 // so this script is used to preserve the keys that we need.
@@ -16,6 +17,19 @@ const appId = packageInfo.build.appId;
 delete packageInfo.build;
 packageInfo.build = { appId: appId };
 
+let branch;
+let hash;
+try {
+	branch = execSync('git branch --show-current').toString().trim();
+	hash   = execSync('git log --pretty="%h" -1').toString().trim();
+}
+catch(err) {
+	console.warn("Could not get git info", err);
+}
+if (typeof branch !== 'undefined' && typeof hash !== 'undefined') {
+	packageInfo.git = { branch: branch, hash: hash };
+}
+
 let fileContent = "// Auto-generated by compile-package-info.js\n// Do not change directly\nconst packageInfo = " + JSON.stringify(packageInfo, null, 4) + ';';
 fileContent += "\n";
 fileContent += "module.exports = packageInfo;";