Add compatibility shim for removesuffix.

backports/tarfile/__init__.py

@@ -48,6 +48,8 @@
 import re
 import warnings
 
+from .compat.py38 import removesuffix
+
 try:
     import pwd
 except ImportError:
@@ -1365,7 +1367,7 @@ def _proc_gnulong(self, tarfile):
         # Remove redundant slashes from directories. This is to be consistent
         # with frombuf().
         if next.isdir():
-            next.name = next.name.removesuffix("/")
+            next.name = removesuffix(next.name, "/")
 
         return next
 

backports/tarfile/compat/py38.py

@@ -0,0 +1,24 @@
+import sys
+
+
+if sys.version_info < (3, 9):
+
+    def removesuffix(self, suffix):
+        # suffix='' should not call self[:-0].
+        if suffix and self.endswith(suffix):
+            return self[: -len(suffix)]
+        else:
+            return self[:]
+
+    def removeprefix(self, prefix):
+        if self.startswith(prefix):
+            return self[len(prefix) :]
+        else:
+            return self[:]
+else:
+
+    def removesuffix(self, suffix):
+        return self.removesuffix(suffix)
+
+    def removeprefix(self, prefix):
+        return self.removeprefix(prefix)