我在使用 apt 时收到此警告：
$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages have been kept back:
python3-protobuf
0 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.
为了修复它，我正在尝试：
$ sudo apt-get install python3-protobuf
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:
python3-protobuf : Depends: libprotobuf15 but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
所以它要求安装libprotobuf15。我已经安装了libprotobuf10。
当我尝试安装时libprotobuf15，我发现许多看起来像系统包的包将被删除：
$ sudo apt-get install libprotobuf15
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
bamfdaemon compiz-core compiz-plugins-default gazebo9-common gir1.2-accounts-1.0 gir1.2-clutter-1.0 gir1.2-cogl-1.0 gir1.2-coglpango-1.0 gir1.2-gdata-0.0
gir1.2-signon-1.0 gtk3-nocsd hud libavdevice57 libbullet2.87 libccd2 libcolumbus1-common libcolumbus1v5 libdbusmenu-qt5-2 libdecoration0 libframe6 libgeis1
libglewmx1.13 libgrail6 libgsettings-qt1 libgtk3-nocsd0 libignition-common libignition-fuel-tools1-1 libignition-math4 libmetacity1 libnux-4.0-0 libnux-4.0-common
libqtpropertybrowser4 libsdformat6 libsignon-glib1 libsimbody3.5v5 libspnav0 libtar0 libunity-core-6.0-9 libunity-misc4 libzeitgeist-1.0-1 metacity-common
nux-tools python3-blinker python3-feedparser python3-jwt python3-oauthlib sdformat-sdf session-shortcuts unity-asset-pool unity-lens-applications unity-lens-files
unity-lens-music unity-lens-photos unity-lens-video unity-schemas unity-scope-calculator unity-scope-chromiumbookmarks unity-scope-colourlovers
unity-scope-devhelp unity-scope-firefoxbookmarks unity-scope-home unity-scope-manpages unity-scope-openclipart unity-scope-texdoc unity-scope-tomboy
unity-scope-video-remote unity-scope-virtualbox unity-scope-yelp unity-scope-zotero unity-scopes-master-default unity-scopes-runner
Use 'sudo apt autoremove' to remove them.
The following additional packages will be installed:
python3-protobuf
The following packages will be REMOVED:
compiz compiz-gnome evolution-data-server gazebo9 gazebo9-plugin-base gdm3 gnome-shell gnome-shell-extension-dash-to-panel gnome-shell-extensions gnome-todo
libcompizconfig0 libebook-1.2-19 libebook-contacts-1.2-2 libedata-book-1.2-25 libgazebo9 libignition-msgs libignition-transport4 libphonenumber7 libprotobuf10
libprotoc10 ubuntu-desktop ubuntu-session ubuntu-unity-desktop unity unity-session unity-tweak-tool
The following NEW packages will be installed:
libprotobuf15
The following packages will be upgraded:
python3-protobuf
1 upgraded, 1 newly installed, 26 to remove and 0 not upgraded.
Need to get 1'019 kB of archives.
After this operation, 73.8 MB disk space will be freed.
Do you want to continue? [Y/n]
继续操作是否安全，尤其是关于“ubuntu”和“unity”软件包（我在安装 18.04 版本后立即安装了“unity”，因为我使用的是笔记本电脑，而且我关心垂直空间）？
你也遇到过这种情况吗？