initialize compression globally for non-“concat” archives

diff --git a/deltatar/tarfile.py b/deltatar/tarfile.py
index a2d21c4..aef4faf 100644 (file)
--- a/deltatar/tarfile.py
+++ b/deltatar/tarfile.py
@@ -464,7 +464,9 @@ class _Stream:
                 self.zlib = zlib
                 if mode == "r":
                     self._init_read_gz()
-                self.exception = zlib.error # XXX what for? seems unused
+                    self.exception = zlib.error
+                elif mode == "w" and concat_stream is False:
+                    self._new_gz_block()
                 self.crc = zlib.crc32(b"") & 0xFFFFffff
 
             elif comptype == "bz2":