fix usage exception

buildozer/__init__.py

@@ -892,7 +892,10 @@ class Buildozer(object):
         print('Available targets:')
         targets = list(self.targets())
         for target, m in targets:
-            doc = m.__doc__.strip().splitlines()[0].strip()
+            try:
+                doc = m.__doc__.strip().splitlines()[0].strip()
+            except Exception:
+                doc = '<no description>'
             print('  {0:<18} {1}'.format(target, doc))
 
         print('')

buildozer/targets/android.py

@@ -1,5 +1,5 @@
 '''
-Android target, based on python-for-android project
+Android target, based on python-for-android project (old toolchain)
 '''
 #
 # Android target

buildozer/targets/android_new.py

@@ -1,4 +1,7 @@
 # coding=utf-8
+'''
+Android target, based on python-for-android project (new toolchain)
+'''
 
 from buildozer.targets.android import TargetAndroid
 from os.path import join, expanduser

buildozer/targets/ios.py

@@ -1,5 +1,5 @@
 '''
-iOS target, based on kivy-ios project. (not working yet.)
+iOS target, based on kivy-ios project
 '''
 
 import sys