Kexec reboot doesn't work on 18.04 non-EFI system

Unclear whether to report it against kexec-tools or systemd.

After upgrading to Ubuntu 18.04, the „systemctl kexec” command gives the following error message:
Cannot find the ESP partition mount point.

What's interesting is that strace shows that systemctl tries to find the EFI partition before it emits the error message, like it was expecting an EFI system. My laptop is not capable of EFI, and it wasn't a problem for previous Ubuntu releases – the „systemctl kexec” command worked fine before.

Here is my systemd version:

root@thinkpad:~# systemd --version
systemd 237
+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD -IDN2 +IDN -PCRE2 default-hierarchy=hybrid

And my kexec-tools version is 1:2.0.16-1ubuntu1.

I attached an strace output.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: kexec-tools 1:2.0.16-1ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17
Uname: Linux 4.15.0-20-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sun May 13 12:48:25 2018
InstallationDate: Installed on 2014-06-10 (1432 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=hu_HU.UTF-8
 SHELL=/bin/bash
SourcePackage: kexec-tools
UpgradeStatus: Upgraded to bionic on 2018-05-12 (0 days ago)