Description of problem:
systemd.spec of https://dl.fedoraproject.org/pub/fedora/linux/releases/23/Everything/source/SRPMS/s/systemd-222-7.fc23.src.rpm greps and seds /etc/fstab unconditionally but it might be missing when you install systemd to an empty dir while bootstrapping Fedora. And you will get File not found error. Fortunately it does not break anything.

Version-Release number of selected component (if applicable):
222-8.fc23.x86_64

How reproducible:
always

Steps to Reproduce:
1. mkdir /mnt/fedora23
2. dnf --installroot=/mnt/fedora23 --releasever=23 install fedora-release dnf

Actual results:
no errors

Expected results:
errors while installing systemd
grep: /etc/fstab: No such file or directory
sed: can't read /etc/fstab: No such file or directory

Additional info:
these are the lines of the systemd.spec responsible for the error
# Remove spurious /etc/fstab entries from very old installations
# https://bugzilla.redhat.com/show_bug.cgi?id=1009023
grep -v -E -q '^(devpts|tmpfs|sysfs|proc)' /etc/fstab || \
    sed -i.rpm.bak -r '/^devpts\s+\/dev\/pts\s+devpts\s+defaults\s+/d; /^tmpfs\s+\/dev\/shm\s+tmpfs\s+defaults\s+/d; /^sysfs\s+\/sys\s+sysfs\s+defaults\s+/d; /^proc\s+\/proc\s+proc\s+defaults\s+/d' /etc/fstab || :