[FS#675] Packages and Packages.gz have different content, cause opkg update fail when configured with src/gz

[LEDE Bugs]

The following task has a new comment added:

FS#675 - Packages and Packages.gz have different content, cause opkg update fail when configured with src/gz
User who did this - jwfang (jwfang)

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my router is Lenovo y1 and using packages from the following URL:
https://downloads.lede-project.org/releases/17.01.0/targets/ramips/mt7620/packages/
https://downloads.lede-project.org/releases/17.01.0/packages/mipsel_24kc/

i can reproduce with the following commands:

root at LEDE:/tmp/t# wget http://downloads.lede-project.org/releases/17.01.0/packages/mipsel_24kc/base/Packages
Downloading 'http://downloads.lede-project.org/releases/17.01.0/packages/mipsel_24kc/base/Packages'
Connecting to 148.251.78.235:80
Writing to 'Packages'
Packages             100% |*******************************|   175k  0:00:00 ETA
Download completed (179689 bytes)
root at LEDE:/tmp/t# wget http://downloads.lede-project.org/releases/17.01.0/packages/mipsel_24kc/base/Packages.gz
Downloading 'http://downloads.lede-project.org/releases/17.01.0/packages/mipsel_24kc/base/Packages.gz'
Connecting to 148.251.78.235:80
Redirected to /downloads.lede-project.org/c3pr90ntc0td/releases/17.01.0/packages/mipsel_24kc/base/Packages.gz on 211.162.74.233
Writing to 'Packages.gz'
Packages.gz          100% |*******************************| 47270   0:00:00 ETA
Download completed (47270 bytes)
root at LEDE:/tmp/t# zcat Packages.gz > PackagesGZ
root at LEDE:/tmp/t# ls -l
-rw-r--r--    1 root     root        179689 Apr  4 21:45 Packages
-rw-r--r--    1 root     root         47270 Apr  4 21:45 Packages.gz
-rw-r--r--    1 root     root        177874 Apr  4 21:45 PackagesGZ
root at LEDE:/tmp/t# sha256sum Packages PackagesGZ
1fd6c5a8cac6f4d689c01b134ab228a5bc160a5ca47e70ab9b209bfe8f4383a5  Packages
0c6b3c696bcfab0a07544d5dd9929298aaf1a65090c2adfef6c9286060fff87f  PackagesGZ
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=675#comment2313