It's very funny. When I downloaded the extension of my own, I got an error saying 'this is not a tar archive.'. When I downloaded it from the google code, it is OK. Then I compared two files as follows.
Correct one from google:
0000000 8b1f 0008 10df 4a43 0300 5ced 73eb b71b
0000020 9711 4eec b25b 2fd3 c99d 2be4 61ac d243
0000040 24a6 99be a290 5a1c 1da2 244e a552 b8e8
0000060 a66e 39c3 41de 8de2 778f 1dcc 47a8 fe3b
0000100 e9d0 963f aabf bb9f e00b 249e d945 e892
0000120 be24 35b5 3bba 162c 058f bf16 1605 14d2
0000140 eca6 3c6e e52c 6a81 8ab5 5df8 872d 4b7e
0000160 28da 8a14 7cc5 90b5 952f 1b0a 42f9 5aa1
0000200 6eae ca90 d703 d38b 61cc 4d8a 86c8 bca3
0000220 d99b be8a 6f94 fa55 94af d434 a33f db0e
Wrong one from Yii extension:
0000000 8b1f 0008 0000 0000 0300 2201 dd0f 1ff0
0000020 088b df00 4310 004a ed03 eb5c 1b73 11b7
0000040 ec97 5b4e d3b2 9d2f e4c9 ac2b 4361 a6d2
0000060 be24 9099 1ca2 a25a 4e1d 5224 e8a5 6eb8
0000100 c3a6 de39 e241 8f8d cc77 a81d 3b47 d0fe
0000120 3fe9 bf96 9faa 0bbb 9ee0 4524 92d9 24e8
0000140 b5be ba35 2c3b 8f16 1605 05bf d216 a614
0000160 6eec 2c3c 81e5 b56a f88a 2d5d 7e87 da4b
0000200 1428 c58a b57c 2f90 0a95 f91b a142 ae5a
0000220 906e 03ca 8bd7 ccd3 8a61 c84d a386 9bbc
Some extra bytes are added to the wrong file that has 23 bytes bigger in size.
I have deleted it and tried again, it is the same situation. Can you other guys do 'tar tvzf' to my extension?