Update fails if the path contains non-ascii characters

[std66]

Make sure you are using the latest version: run youtube-dl --version and ensure your version is 2018.12.17. If it's not, read this FAQ entry and update. Issues with outdated version will be rejected.

• [invalid requirement] I've verified and I assure that I'm running youtube-dl 2018.12.17
  Important: I had to test the issue with an older version because the issue is related to the update process. I am using version 2018.11.23.

Before submitting an issue make sure you have:

• At least skimmed through the README, most notably the FAQ and BUGS sections
• Searched the bugtracker for similar issues including closed ones
• Checked that provided video/audio/playlist URLs (if any) are alive and playable in a browser

What is the purpose of your issue?

• Bug report (encountered problems with youtube-dl)
• Site support request (request for adding support for a new site)
• Feature request (request for a new functionality)
• Question
• Other

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The following sections concretize particular purposed issues, you can erase any section (the contents between triple ---) not applicable to your issue

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If the purpose of this issue is a bug report, site support request or you are not completely sure provide the full verbose output as follows:

StdOut:

Updating to version 2018.12.17 ...
Waiting for file handle to be closed ...
Updated youtube-dl to version 2018.12.17.

StdErr:

[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['-U', '--verbose']
[debug] Encodings: locale cp1250, fs mbcs, out cp1250, pref cp1250
[debug] youtube-dl version 2018.11.23
[debug] Python version 3.4.4 (CPython) - Windows-10-10.0.17134
[debug] exe versions: ffmpeg N-72805-g913685f, ffprobe N-72805-g913685f
[debug] Proxy map: {}
The system cannot find the file specified.

Exit code: 0

Description of your issue, suggested solution and other information

1. Create the directory "C:\PróbaKönyvtár". This must be the working directory in the following steps.
2. Copy an older version of youtube-dl.exe to the working directory.
3. Execute command in command line: youtube-dl -U

Actual results:
An error message will be received with the message "The system cannot find the file specified." and youtube-dl.exe.new remains in the directory. Invoking youtube-dl --version will return the old version number representing that the update process has failed. The exit code is 0.

Expected results:
The command succeeds and youtube-dl.exe is updated to the new version. Also, the update process should check the results of the IO operations during update. In case of failure the exit code is not 0.