Bug with GnuPG 2.1.1 on Windows 7 x64

[Robert J. Hansen]

On a Fedora 20 box running GnuPG 2.0.20-something (.25?), I made a 
backup of several sensitive files -- including my keyrings -- and used 
GnuPG to symmetrically encrypt the archive.  I can decrypt this archive 
on every 2.0.whatever installation I have, but my one GnuPG 2.1.1 
installation, on a Windows 7 x64 box, can't decrypt it.

C:\Users\rjh\Desktop>gpg -vvvv backup.tar.xz.gpg
gpg: using character set 'CP437'
# off=0 ctb=85 tag=1 hlen=3 plen=526
:pubkey enc packet: version 3, algo 16, keyid B8A6B74C001892C2
         data: [2044 bits]
         data: [2047 bits]
gpg: public key is 001892C2
# off=529 ctb=85 tag=1 hlen=3 plen=268
:pubkey enc packet: version 3, algo 1, keyid E5B12DCFA1AC6FC0
         data: [2047 bits]
gpg: public key is A1AC6FC0
# off=800 ctb=8c tag=3 hlen=2 plen=46
:symkey enc packet: version 4, cipher 2, s2k 3, hash 2, seskey 256 bits
         salt 018490B8887579F9, count 65536 (96)
gpg: 3DES encrypted session key
# off=848 ctb=d2 tag=18 hlen=2 plen=0 partial new-ctb
:encrypted data packet:
         length: unknown
         mdc_method: 2
gpg: encrypted with 1 passphrase
gpg: encrypted with RSA key, ID A1AC6FC0
gpg: encrypted with ELG key, ID 001892C2
gpg: encrypted with unknown algorithm 64
gpg: decryption failed: Invalid cipher algorithm



... What's going on here?  It seems like an alarming regression if GnuPG 
2.1.1 is unable to decrypt symmetrically-encrypted files made with GnuPG 
2.0.x.