*: Zodbdump format is semi text-binary: Mark it as such + handle zdump output as binary

Zodbdump format is already described as semi text-binary in top-level
zodbdump.py documentation. However zdump() docstring was referring to it
as "text". Fix it and use binary to handle places where zdump is
loaded/saved.

zodbtools/test/gen_testdata.py

@@ -276,7 +276,7 @@ def main():
             dbname += "_!zext"
         gen_testdb("%s.fs" % dbname, zext=zext)
         stor = FileStorage("%s.fs" % dbname, read_only=True)
-        with open("%s.zdump.ok" % dbname, "w") as f:
+        with open("%s.zdump.ok" % dbname, "wb") as f:
             zodbdump(stor, None, None, out=f)
 
 if __name__ == '__main__':

zodbtools/test/test_commit.py

 # -*- coding: utf-8 -*-
-# Copyright (C) 2018-2019  Nexedi SA and Contributors.
+# Copyright (C) 2018-2020  Nexedi SA and Contributors.
 #                          Kirill Smelkov <kirr@nexedi.com>
 #                          Jérome Perrin <jerome@nexedi.com>
 #
@@ -58,7 +58,7 @@ def test_zodbcommit(zext):
     zodbdump(stor, p64(u64(head)+1), None, out=buf)
     dumped = buf.getvalue()
 
-    assert dumped == ''.join([_.zdump() for _ in (t1, t2)])
+    assert dumped == b''.join([_.zdump() for _ in (t1, t2)])
 
     # ObjectCopy. XXX zodbcommit handled ObjectCopy by actually copying data,
     # not referencing previous transaction via backpointer.

zodbtools/test/test_dump.py

 # -*- coding: utf-8 -*-
-# Copyright (C) 2017-2019  Nexedi SA and Contributors.
+# Copyright (C) 2017-2020  Nexedi SA and Contributors.
 #                          Kirill Smelkov <kirr@nexedi.com>
 #                          Jérome Perrin <jerome@nexedi.com>
 #
@@ -39,7 +39,7 @@ def test_zodbdump(zext):
     zkind = '_!zext' if zext.disabled else ''
     stor  = FileStorage('%s/testdata/1%s.fs' % (tdir, zkind), read_only=True)
 
-    with open('%s/testdata/1%s.zdump.ok' % (tdir, zkind)) as f:
+    with open('%s/testdata/1%s.zdump.ok' % (tdir, zkind), 'rb') as f:
         dumpok = f.read()
 
     out = BytesIO()
@@ -116,7 +116,7 @@ extension "qqq"
 
     assert r.readtxn() == None
 
-    z = ''.join([_.zdump() for _ in (t1, t2)])
+    z = b''.join([_.zdump() for _ in (t1, t2)])
     assert z == in_
 
     # unknown hash function

zodbtools/zodbdump.py

@@ -452,8 +452,8 @@ class Transaction(object):
     def _extension(self):
         return self.extension
 
-    # zdump returns text representation of a record in zodbdump format.
-    def zdump(self):
+    # zdump returns semi text-binary representation of a record in zodbdump format.
+    def zdump(self): # -> bytes
         z  = 'txn %s %s\n' % (ashex(self.tid), qq(self.status))
         z += 'user %s\n' % qq(self.user)
         z += 'description %s\n' % qq(self.description)