If during the installation I select to install the package open-isns, I
found this error in /var/log/zypp/history:

# 2015-12-09 21:09:12 open-isns-0.90-35.2.x86_64.rpm installed ok
# Additional rpm output:
# /var/tmp/rpm-tmp.JxwMaX: line 4: mkdir: command not found
# /var/tmp/rpm-tmp.JxwMaX: line 8: touch: command not found
# /var/tmp/rpm-tmp.JxwMaX: line 8: touch: command not found
# /var/tmp/rpm-tmp.0R91GT: line 3: mkdir: command not found
# /var/tmp/rpm-tmp.0R91GT: line 8: touch: command not found
# /var/tmp/rpm-tmp.0R91GT: line 8: touch: command not found
# /var/tmp/rpm-tmp.0R91GT: line 27: sed: command not found
# /var/tmp/rpm-tmp.0R91GT: line 27: sed: command not found
# warning: %post(open-isns-0.90-35.2.x86_64) scriptlet failed, exit status 127
# 
2015-12-09
21:09:12|install|open-isns|0.90-35.2|x86_64|root@virtual1|openSUSE-42.1-0|6b3647fc93b1aa111b08b90683d45a03e8503fda|

The problem is that open-isns is installed before coreutils and sed and at that
time the binaries touch, mkdir (coreutils) and sed are not available yet.

A possible fix is to add two lines in open-iscsi.spec:

 PreReq:         %fillup_prereq %insserv_prereq
+PreReq:         coreutils
+PreReq:         sed