Handle change.files entries with nested lists

I don't know where these come from, but they're easy enough to handle.
Fixes buildbot#915.

master/buildbot/db/schema/v1.py

@@ -297,7 +297,22 @@ def remove_none(x):
         for link in change.links:
             cursor.execute(util.sql_insert(self.dbapi, 'change_links', ('changeid', 'link')),
                           (change.number, link))
-        for filename in change.files:
+
+        # sometimes change.files contains nested lists -- why, I do not know!  But we deal with
+        # it all the same - see bug #915. We'll assume for now that change.files contains *either*
+        # lists of filenames or plain filenames, not both.
+        def flatten(l):
+            if l and type(l[0]) == list:
+                rv = []
+                for e in l:
+                    if type(e) == list:
+                        rv.extend(e)
+                    else:
+                        rv.append(e)
+                return rv
+            else:
+                return l
+        for filename in flatten(change.files):
             cursor.execute(util.sql_insert(self.dbapi, 'change_files', ('changeid', 'filename')),
                           (change.number, filename))
         for propname,propvalue in change.properties.properties.items():

master/buildbot/test/regressions/test_import_weird_changes.py

@@ -0,0 +1,51 @@
+import os
+import shutil
+import cPickle
+
+from twisted.trial import unittest
+
+from buildbot.changes.changes import Change, OldChangeMaster
+
+from buildbot.db.schema import manager
+from buildbot.db.dbspec import DBSpec
+from buildbot.db.connector import DBConnector
+
+class TestWeirdChanges(unittest.TestCase):
+    def setUp(self):
+        self.basedir = "WeirdChanges"
+        if os.path.exists(self.basedir):
+            shutil.rmtree(self.basedir)
+        os.makedirs(self.basedir)
+
+        # Now try the upgrade process, which will import the old changes.
+        self.spec = DBSpec.from_url("sqlite:///state.sqlite", self.basedir)
+
+        self.db = DBConnector(self.spec)
+        self.db.start()
+
+    def tearDown(self):
+        if self.db:
+            self.db.stop()
+        if os.path.exists(self.basedir):
+            shutil.rmtree(self.basedir)
+
+    def mkchanges(self, changes):
+        import buildbot.changes.changes
+        cm = buildbot.changes.changes.OldChangeMaster()
+        cm.changes = changes
+        return cm
+
+    def testListsAsFilenames(self):
+        # Create changes.pck
+        changes = [Change(who=u"Frosty the \N{SNOWMAN}".encode("utf8"),
+            files=[["foo","bar"],['bing']], comments=u"Frosty the \N{SNOWMAN}".encode("utf8"),
+            branch="b1", revision=12345)]
+        cPickle.dump(self.mkchanges(changes), open(os.path.join(self.basedir,
+            "changes.pck"), "wb"))
+
+        sm = manager.DBSchemaManager(self.spec, self.basedir)
+        sm.upgrade(quiet=True)
+
+        c = self.db.getChangeNumberedNow(1)
+
+        self.assertEquals(sorted(c.files), sorted([u"foo", u"bar", u"bing"]))