Bug has also been reported by Marcus Klein:

---------- Original Message ----------
From: bugreport@novell.com
To: bugreport@novell.com, marcus.klein@open-xchange.com
Date: August 14, 2015 at 3:15 PM
Subject: Bug Report Submission

The following bug report has been submitted:


Name: Marcus Klein
Company: Open-Xchange GmbH
Address: Martinstr. 41
Email: marcus.klein@open-xchange.com
Phone: +49 2761 75252-18
Product: SUSE Linux Enterprise Server 12
Patch Level: latest
Defect: # rpm --import http://software.open-xchange.com/oxbuildkey.pub
error: http://software.open-xchange.com/oxbuildkey.pub: import read failed(2).

Using strace I found out, that rpm uses curl internally:
[pid 6320] execve("/usr/bin/curl", ["/usr/bin/curl", "--silent", "--show-error", "--fail", "--location", "-o", "/var/tmp/rpm-tmp.1roNpA", "http://software.open-xchange.com"...], [/ 46 vars /]) = -1 ENOENT (No such file or directory)

To solve this issue the rpm package should get a dependency on curl.
Other Software and Versions Being Used: none, just SUSE Linux Enterprise Server 12
Steps to Duplicate: 1. Install a minimal SUSE Linux Enterprise Server 12 without having package curl installed.
2. Try to import a build key of a third party software repository with "rpm --import"
Other Scenarios: Yes
Environment Description: Single box having a minimal SUSE Linux Enterprise Server 12 installed.
Problem Environment: Production and Testing
Testing Environment: Yes
Fix: Package curl needs to be installed. This should be done automatically with a package dependency on the rpm package.

I'd rather add a "you need to install curl" error message before adding a new dependency on curl. (The manpage does not even mention that you can specify an url with --import, so I might as well make that an error...)