I have taken the list of packages in 15-SP1:GA and SLE-15:GA
and checked for their status in Leap:15.1 with fallbacks to the above and to Factory as last resort.
<p>
<a href="sle-15-report.txt">The output</a>  is in CSV format with 3 bits describing every source package:
</p>
<pre>
1. unreproducible
 means building it twice myself produced different results.
 This varies hostname, date+year, CPU, parallelism with the '<a href="https://github.com/bmwiedemann/reproducibleopensuse/blob/master/rbk">rbk</a>' script.
 See <a href="https://bugzilla.opensuse.org/show_bug.cgi?id=1081754">boo#1081754</a> and dependent bugs.

2. unverifiable
 means downloading the OBS build result and building it once locally
 produced different results.
 Can be a result of the above unreproducible bit or other issues
 <a href="https://github.com/openSUSE/pesign-obs-integration/issues/9">pesign OBS integration bug</a>
 <a href="https://github.com/rpm-software-management/rpm/pull/485">rpm debuginfo sort</a>

3. nonoarch
 means noarch packages differed between architectures
 See <a href="https://bugzilla.opensuse.org/show_bug.cgi?id=1109534">boo#1109534</a> and dependent bugs.

</pre>
Several issues have meanwhile been fixed in Factory.
Some bits might be inaccurate.
<br>
As of 2019-02-04, of 3571 SLE packages, 460 have some issue. 271 of those are only affected by the the nonoarch problem.
92 do not give reproducible build results.