Merge from 3.2: Issue #12926: Fix a bug in tarfile's link extraction.

On platforms that do not support (symbolic) links, tarfile offers a
work-around and extracts a link in an archive as the regular file the link is
pointing to. On other platforms, this code was accidentally executed even
after the link had been successfully extracted which failed due to the already
existing link.

Lib/tarfile.py

@@ -2340,12 +2340,6 @@ class TarFile(object):
                     self._extract_member(self._find_link_target(tarinfo),
                                          targetpath)
         except symlink_exception:
-            if tarinfo.issym():
-                linkpath = os.path.join(os.path.dirname(tarinfo.name),
-                                        tarinfo.linkname)
-            else:
-                linkpath = tarinfo.linkname
-        else:
             try:
                 self._extract_member(self._find_link_target(tarinfo),
                                      targetpath)

Misc/NEWS

@@ -422,6 +422,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #12926: Fix a bug in tarfile's link extraction.
+
 - Issue #13696: Fix the 302 Relative URL Redirection problem.
 
 - Issue #13636: Weak ciphers are now disabled by default in the ssl module