[cmake-developers] [patch] One more pattern for extracting file name from URL

[Ben Boeckel]

On Tue, Jul 05, 2016 at 19:49:46 +0300, Ruslan Baratov wrote:
> Archive can be unpacked by "cmake -E tar xf" which detect type 
> automatically as far as I understand. At least this one used internally 
> by ExternalProject (see the testing I've made before).

CMake is not my go-to tool for extracting files though (and similarly
for others I imagine), so running `tar xf archive.tar` and getting an
error because it is actually a .tar.gz (or even a .zip) file is not
nice.

> So even if it seems that archive name is `|archive.tar.gz` it should be 
> downloaded to 
> `||gitlab-ce-v8.9.3-5e546d9b4728fc9c9623992a678cbea9eb2098f1.tar.gz`. So 
> I think it's easily can be file with another extension.|

Here's another idea: add an `OUTPUT_FILE <var>` keyword argument to
`file(DOWNLOAD)` to get the actual filename after content disposition
resolution (probably similar for 30x rewrites). This would also be
useful for things other than ExternalProject.

--Ben