Revision 875597

Fix 'svnadmin hotcopy' of packed repositories.

To reproduce (with vanilla trunk):

	#!/bin/sh
	rm -rf Foo Bar Bar2
	svnadmin create Foo
	sed -i 's/sharded 1000/sharded 1/' Foo/db/format
	svnadmin hotcopy Foo Bar
	svnadmin pack Foo
	echo "=== *Now* it will error:"
	svnadmin hotcopy Foo Bar2
	
The bug was found by svnadmin_tests.py with -DPACK_AFTER_EVERY_COMMIT.  (It
did not reproduce if only --fsfs-packing was used to enable packing in the
post-commit hook in the tests.)

* subversion/libsvn_fs_fs/fs_fs.c
  (svn_fs_fs__hotcopy):
    Account for packed shards when copying the revs/ directory.