checkupdates: don't fail when we can't init submodules

Later revisions might have removed the submodules so we want to keep
going when there are no submodules present.
We still abort when there is an error initializing submodules.

Fixes fdroid/fdroidserver#231

fdroidserver/checkupdates.py

@@ -33,7 +33,7 @@ import copy
 from . import _
 from . import common
 from . import metadata
-from .exception import VCSException, FDroidException, MetaDataException
+from .exception import VCSException, NoSubmodulesException, FDroidException, MetaDataException
 
 
 # Check for a new version by looking at a document retrieved via HTTP.
@@ -110,8 +110,7 @@ def check_tags(app, pattern):
 
         last_build = app.get_last_build()
 
-        if last_build.submodules:
-            vcs.initsubmodules()
+        try_init_submodules(app, last_build, vcs)
 
         hpak = None
         htag = None
@@ -207,8 +206,7 @@ def check_repomanifest(app, branch=None):
         if len(app.builds) > 0:
             last_build = app.builds[-1]
 
-        if last_build.submodules:
-            vcs.initsubmodules()
+        try_init_submodules(app, last_build, vcs)
 
         hpak = None
         hver = None
@@ -300,6 +298,19 @@ def check_gplay(app):
     return (version.strip(), None)
 
 
+def try_init_submodules(app, last_build, vcs):
+    """Try to init submodules if the last build entry used them.
+    They might have been removed from the app's repo in the meantime,
+    so if we can't find any submodules we continue with the updates check.
+    If there is any other error in initializing them then we stop the check.
+    """
+    if last_build.submodules:
+        try:
+            vcs.initsubmodules()
+        except NoSubmodulesException:
+            logging.info("No submodules present for {}".format(app.Name))
+
+
 # Return all directories under startdir that contain any of the manifest
 # files, and thus are probably an Android project.
 def dirs_with_manifest(startdir):