Be more lenient of symlinked /bin/sh inside the chroot (#16239)

Symlinks inside of the chroot were failng because we weren't able to
    determine if they were pointing to a real file or not.  We could write
    some complicated code to walk the symlink path taking into account where
    the root of the tree is but that could be fragile.  Since this is just
    a sanity check, instead we just assume that the chroot is fine if we
    find that /bin/sh in the chroot is a symlink.  Can revisit if it turns
    out that many chroots have a /bin/sh that's a broken symlink.

    Fixes #16097

lib/ansible/plugins/connection/chroot.py

@@ -63,7 +63,11 @@ class Connection(ConnectionBase):
             raise AnsibleError("%s is not a directory" % self.chroot)
 
         chrootsh = os.path.join(self.chroot, 'bin/sh')
-        if not is_executable(chrootsh):
+        # Want to check for a usable bourne shell inside the chroot.
+        # is_executable() == True is sufficient.  For symlinks it
+        # gets really complicated really fast.  So we punt on finding that
+        # out.  As long as it's a symlink we assume that it will work
+        if not (is_executable(chrootsh) or (os.path.lexists(chrootsh) and os.path.islink(chrootsh))):
             raise AnsibleError("%s does not look like a chrootable dir (/bin/sh missing)" % self.chroot)
 
         self.chroot_cmd = distutils.spawn.find_executable('chroot')