py3: make tests/svn-safe-append.py compatible with python 3

Differential Revision: https://phab.mercurial-scm.org/D4671

tests/svn-safe-append.py

@@ -1,28 +1,32 b''
 #!/usr/bin/env python
 
 from __future__ import absolute_import
 
 __doc__ = """Same as `echo a >> b`, but ensures a changed mtime of b.
 Without this svn will not detect workspace changes."""
 
 import os
 import stat
 import sys
 
-text = sys.argv[1]
-fname = sys.argv[2]
+if sys.version_info[0] >= 3:
+    text = os.fsencode(sys.argv[1])
+    fname = os.fsencode(sys.argv[2])
+else:
+    text = sys.argv[1]
+    fname = sys.argv[2]
 
 f = open(fname, "ab")
 try:
     before = os.fstat(f.fileno())[stat.ST_MTIME]
     f.write(text)
-    f.write("\n")
+    f.write(b"\n")
 finally:
     f.close()
 inc = 1
 now = os.stat(fname)[stat.ST_MTIME]
 while now == before:
     t = now + inc
     inc += 1
     os.utime(fname, (t, t))
     now = os.stat(fname)[stat.ST_MTIME]