Ceph

On clean-installed Ubuntu 18.04.5 LTS, after git clone and checkout v14.2.20, running install-debs.sh claims following message:

Hit:1 http://us.archive.ubuntu.com/ubuntu bionic InRelease
Hit:2 http://us.archive.ubuntu.com/ubuntu bionic-updates InRelease
Hit:3 http://security.ubuntu.com/ubuntu bionic-security InRelease
Hit:4 http://us.archive.ubuntu.com/ubuntu bionic-backports InRelease
Ign:5 https://chacra.ceph.com/r/libboost/master/1d7c7a00cc3f37e340bae0360191a757b44ec80c/ubuntu/bionic/flavors/default bionic InRelease
Get:6 https://chacra.ceph.com/r/libboost/master/1d7c7a00cc3f37e340bae0360191a757b44ec80c/ubuntu/bionic/flavors/default bionic Release [7582 B]
Ign:7 https://chacra.ceph.com/r/libboost/master/1d7c7a00cc3f37e340bae0360191a757b44ec80c/ubuntu/bionic/flavors/default bionic Release.gpg
Get:8 https://chacra.ceph.com/r/libboost/master/1d7c7a00cc3f37e340bae0360191a757b44ec80c/ubuntu/bionic/flavors/default bionic/main i386 Packages [556 B]
Get:9 https://chacra.ceph.com/r/libboost/master/1d7c7a00cc3f37e340bae0360191a757b44ec80c/ubuntu/bionic/flavors/default bionic/main amd64 Packages [14.9 kB]
Fetched 23.1 kB in 2s (13.0 kB/s)
Reading package lists... Done
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:
 ceph-libboost-coroutine1.72-dev : Depends: ceph-libboost-coroutine1.72.0 (= 1.72.0-1) but it is not going to be installed
 ceph-libboost-regex1.72-dev : Depends: ceph-libboost-regex1.72.0 (= 1.72.0-1) but it is not going to be installed
 ceph-libboost-thread1.72-dev : Depends: ceph-libboost-thread1.72.0 (= 1.72.0-1) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

And I identified following 2 unmet dependencies related to libstdc++6

The following packages have unmet dependencies:
 ceph-libboost-thread1.72.0 : Depends: libstdc++6 (>= 9) but 8.4.0-1ubuntu1~18.04 is to be installed
E: Unable to correct problems, you have held broken packages.

The following packages have unmet dependencies:
 ceph-libboost-regex1.72.0 : Depends: libstdc++6 (>= 9) but 8.4.0-1ubuntu1~18.04 is to be installed
E: Unable to correct problems, you have held broken packages.