[minor] [installer] check if app and lib are cloned before proceeding
diff --git a/install_erpnext.py b/install_erpnext.py
index 786b3a2..a10ce10 100644
--- a/install_erpnext.py
+++ b/install_erpnext.py
@@ -193,12 +193,16 @@
 		print "Cloning erpnext"
 		exec_in_shell("cd %s && git clone https://github.com/webnotes/erpnext.git app" % install_path)
 		exec_in_shell("cd app && git config core.filemode false")
+		if not os.path.exists(app):
+			raise Exception, "Couldn't clone erpnext repository"
 	
 	lib = os.path.join(install_path, "lib")
 	if not os.path.exists(lib):
 		print "Cloning wnframework"
 		exec_in_shell("cd %s && git clone https://github.com/webnotes/wnframework.git lib" % install_path)
 		exec_in_shell("cd lib && git config core.filemode false")
+		if not os.path.exists(lib):
+			raise Exception, "Couldn't clone wnframework repository"
 	
 	public = os.path.join(install_path, "public")
 	for p in [public, os.path.join(public, "files"), os.path.join(public, "backups"),