Debug AppVeyor build issues

[kyamagu]

This is only for debugging the AppVeyor CI build issue around chocolatey. Never merge.

[kyamagu]

@amroamroamro Strangely, AppVeyor build succeeds with:

if "%DOXY%" == "yes" ( choco install doxygen.portable -y )

but fails with:

if "%DOXY%" == "yes" ( choco install doxygen.portable -y > nul )

The error is always Command exited with code 404. I don't understand why this happens, as nul redirection works in the other place. Do you have any clue?

[amroamroamro]

hmm I don't know, perhaps we can try to run that line as a Powershell command instead:

  - ps: if ($env:DOXY -match "yes") { choco install doxygen.portable -y > $null }

If it's an intermittent issue with the server, I found this: appveyor/ci#418
It's supposed to run a command with a couple of retries, similar to travis_retry.

Otherwise we can just disable Doxygen stuff for now. I think you can override the environment variable from the AppVeyor UI configuration without having to commit changes to the file.
https://ci.appveyor.com/project/kyamagu/mexopencv/settings/environment
Select "Environment variables > Add variable", create a DOXY environment variable and set its value to no

According to the docs:

Environment variables defined on UI are getting merged with those ones defined in appveyor.yml. Variable values with the same names are getting overridden with values from UI.

[amroamroamro]

or just remove the null redirection if its the real issue here :)

[kyamagu]

@amroamroamro For now, I just disabled doxygen with DOXY=no in the AppVeyor. This looks very weird...