git: improve audit of unknown git modules

When auditing recipes, the potential git checkout was not performed by
Bob. Hence, no information is available if submodules shall be checked
out or not. In this case, assume that potentially present submodules
ought to be checked out recursively. Previously, we assumed that
submodules must not be checked out which is a questionable assumption.

pym/bob/scm/git.py

@@ -908,11 +908,10 @@ def __statusSubmodule(self, workspacePath, status, shouldExist, base = "."):
 
 
     def getAuditSpec(self):
-        extra = {}
-        if self.__submodules:
-            extra['submodules'] = self.__submodules
-            if self.__recurseSubmodules:
-                extra['recurseSubmodules'] = True
+        extra = {
+            'submodules' : self.__submodules,
+            'recurseSubmodules' : self.__recurseSubmodules,
+        }
         return ("git", self.__dir, extra)
 
     def hasLiveBuildId(self):
@@ -987,8 +986,11 @@ class GitAudit(ScmAudit):
 
     async def _scanDir(self, workspace, dir, extra):
         self.__dir = dir
-        self.__submodules = extra.get('submodules', False)
-        self.__recurseSubmodules = extra.get('recurseSubmodules', False)
+        # In case we scan an unkown directry, the `extra` dict will be empty.
+        # In this case we assume submodules exist and are checked our
+        # recursively.
+        self.__submodules = extra.get('submodules')
+        self.__recurseSubmodules = extra.get('recurseSubmodules')
         dir = os.path.join(workspace, dir)
         try:
             remotes = (await check_output(["git", "remote", "-v"],
@@ -1037,7 +1039,8 @@ async def __scanSubmodules(self, dir, shouldExist, base = "."):
         # Normalize subset of submodules
         if isinstance(shouldExist, list):
             shouldExist = set(normPath(p) for p in shouldExist)
-        elif shouldExist:
+        elif shouldExist or shouldExist is None:
+            # If unspecified, we expect all submodules to be present.
             shouldExist = set(normPath(p) for p in allPaths.keys())
         else:
             shouldExist = set()
@@ -1080,8 +1083,8 @@ def _load(self, data):
         self.__commit = data["commit"]
         self.__description = data["description"]
         self.__dirty = data["dirty"]
-        self.__submodules = data.get("submodules", False)
-        self.__recurseSubmodules = data.get("recurseSubmodules", False)
+        self.__submodules = data.get("submodules")
+        self.__recurseSubmodules = data.get("recurseSubmodules")
 
     def dump(self):
         ret = {
@@ -1092,10 +1095,10 @@ def dump(self):
             "description" : self.__description,
             "dirty" : self.__dirty,
         }
-        if self.__submodules:
+        if self.__submodules is not None:
             ret["submodules"] = self.__submodules
-            if self.__recurseSubmodules:
-                ret["recurseSubmodules"] = True
+        if self.__recurseSubmodules is not None:
+            ret["recurseSubmodules"] = self.__recurseSubmodules
         return ret
 
     def getStatusLine(self):