*: Don't use %r to print/report lines/bytes to outside

%r has different output for strings and bytes on python3:

	In [1]: a = 'hello'
	In [2]: b = b'hello'

	In [3]: repr(a)
	Out[3]: "'hello'"

	In [4]: repr(b)
	Out[4]: "b'hello'"

-> Use qq whose output is stable irregardless of whether input is string or bytes.

zodbtools/test/test_dump.py

@@ -130,7 +130,7 @@ obj 0000000000000001 1 xyz:0123 -
 """))
     with raises(RuntimeError) as exc:
         r.readtxn()
-    assert exc.value.args == ("""+5: invalid line: unknown hash function "xyz" ('obj 0000000000000001 1 xyz:0123 -')""",)
+    assert exc.value.args == ("""+5: invalid line: unknown hash function "xyz" ("obj 0000000000000001 1 xyz:0123 -")""",)
 
     # data integrity error
     r = DumpReader(BytesIO("""\

zodbtools/zodbdump.py

 # -*- coding: utf-8 -*-
-# Copyright (C) 2016-2019  Nexedi SA and Contributors.
+# Copyright (C) 2016-2020  Nexedi SA and Contributors.
 #                          Kirill Smelkov <kirr@nexedi.com>
 #                          Jérome Perrin <jerome@nexedi.com>
 #
@@ -320,7 +320,7 @@ class DumpReader(object):
 
     # report a problem found around currently-read line
     def _badline(self, msg):
-        raise RuntimeError("%s+%d: invalid line: %s (%r)" % (_ioname(self._r), self.lineno, msg, self._line))
+        raise RuntimeError("%s+%d: invalid line: %s (%s)" % (_ioname(self._r), self.lineno, msg, qq(self._line)))
 
     # readtxn reads one transaction record from input stream and returns
     # Transaction instance or None at EOF.