Bug 1238298

Found in gzip-1.6-2.fc20.x86_64
Present in gzip-1.6-8.fc23.src.rpm
So affects all intermediate releases. FC21 tagged since FC20 has just officially gone EOL.

See bug 579251 / bug 615303.

less (when used with Fedora's default LESSOPEN handler provided by the less package) used to have a bug whereby "less foo.gz" would work for non-empty compressed files, but return an error and garbage contents when run on a compressed empty file. This was because if the LESSOPEN filter ("|lessopen.sh") produced no output, less assumed that it has failed and opened the original file directly instead. This was fixed by introducing the syntax "||lessopen.sh" which means the script exit status is used to determine success or failure but empty output is otherwise to be trusted. Fedora's LESSOPEN handler in the less package uses this construct and now works.

The gzip package contains the zless script which still uses the "|gzip" construct so still suffers the same problem. "||" was introduced in less-436-7 so should be safe:

* Tue Dec 21 2010 Vojtech Vitek (V-Teq) <vvitek> - 436-7
- Fix for valid empty LESSOPEN pipe output (#579251, #615303)

(Why don't I just use less then? Well, I'm used to switching between boxes with a different distros or older versions of distros on, and fairly often the locally provided less *doesn't* provide a suitable default LESSOPEN that can handle compressed files. So my hands are just used to typing zless instead now...)