Warum kann ich rust-doc nicht installieren?

Ich habe gerade rustc erfolgreich installiert und sah, apt schlug vor, dass ich auch rost-doc habe.

 $ sudo apt install rust-doc Reading package lists... Done Building dependency tree  Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies. rust-doc : Depends: fonts-open-sans but it is not installable E: Unable to correct problems, you have held broken packages. 

Ich nehme an, dass es in meinem Repository einige unechte Abhängigkeiten gibt. Ich bin aber auch besonders besorgt über diese letzte Zeile:

Sie haben defekte Pakete in der Hand.

Ich weiß nicht genau was das bedeutet.

Da ich glaube, dass einige davon von den verwendeten Repositories abhängen, füge ich diese Informationen hinzu:

/etc/apt/sources.list:#deb cdrom:[Linux Mint 18.2 _Sonya_ - Release amd64 20170628]/ xenial contrib main non-free /etc/apt/sources.list.d/maarten-baert-simplescreenrecorder-xenial.list:deb http://ppa.launchpad.net/maarten-baert/simplescreenrecorder/ubuntu xenial main /etc/apt/sources.list.d/maarten-baert-simplescreenrecorder-xenial.list:deb-src http://ppa.launchpad.net/maarten-baert/simplescreenrecorder/ubuntu xenial main /etc/apt/sources.list.d/official-package-repositories.list:# Do not edit this file manually, use Software Sources instead. /etc/apt/sources.list.d/official-package-repositories.list: /etc/apt/sources.list.d/official-package-repositories.list:deb http://packages.linuxmint.com sonya main upstream import backport #id:linuxmint_main /etc/apt/sources.list.d/official-package-repositories.list: /etc/apt/sources.list.d/official-package-repositories.list:deb http://archive.ubuntu.com/ubuntu xenial main restricted universe multiverse /etc/apt/sources.list.d/official-package-repositories.list:deb http://archive.ubuntu.com/ubuntu xenial-updates main restricted universe multiverse /etc/apt/sources.list.d/official-package-repositories.list:deb http://archive.ubuntu.com/ubuntu xenial-backports main restricted universe multiverse /etc/apt/sources.list.d/official-package-repositories.list: /etc/apt/sources.list.d/official-package-repositories.list:deb http://security.ubuntu.com/ubuntu/ xenial-security main restricted universe multiverse /etc/apt/sources.list.d/official-package-repositories.list:deb http://archive.canonical.com/ubuntu/ xenial partner /etc/apt/sources.list.d/vscode.list:### THIS FILE IS AUTOMATICALLY CONFIGURED ### /etc/apt/sources.list.d/vscode.list:# You may comment out this entry, but any other modifications may be lost. /etc/apt/sources.list.d/vscode.list:deb [arch=amd64] http://packages.microsoft.com/repos/vscode stable main 

Als Antwort auf einen Kommentar von David Postill, in dem er vorschlägt, ich installiere fonts-open-sans:

 $ sudo apt-get install fonts-open-sans [sudo] password for sam:  Reading package lists... Done Building dependency tree  Reading state information... Done Package fonts-open-sans is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source  E: Package 'fonts-open-sans' has no installation candidate