Split check in gradle to better warn about GIT / admin right issues

app/build.gradle

@@ -82,6 +82,23 @@ def isMaster = { ->
     return !version.contains('-')
 }
 
+def gitAvailable = { ->
+    StringBuilder stringBuilder = new StringBuilder()
+    try {
+        def stdout = new ByteArrayOutputStream()
+        exec {
+            commandLine 'git', '--version'
+            standardOutput = stdout
+        }
+        String commitObject = stdout.toString().trim()
+        stringBuilder.append(commitObject)
+    } catch (ignored) {
+        return false // NoGitSystemAvailable
+    }
+    return !stringBuilder.toString().isEmpty()
+
+}
+
 def allCommited = { ->
     StringBuilder stringBuilder = new StringBuilder()
     try {
@@ -393,9 +410,13 @@ preBuild.dependsOn copyLibs
 
 printf('--------------\n')
 printf('isMaster: %s\n', isMaster().toString())
+printf('gitAvailable: %s\n', gitAvailable().toString())
 printf('allCommited: %s\n', allCommited().toString())
 printf('--------------\n')
+if (isMaster() && !gitAvailable()) {
+    throw new GradleException('GIT system is not available. On Windows try to run Android Studio as an Administrator. Check if GIT is installed and Studio have permissions to use it')
+}
 if (isMaster() && !allCommited()) {
-    throw new GradleException('There are uncommitted changes or git system is not available. Clone sources again as described in wiki and do not allow gradle update')
+    throw new GradleException('There are uncommitted changes. Clone sources again as described in wiki and do not allow gradle update')
 }