Fail to register a DS instance if no userroot is defined

Issue

Setup a configuration instance called example-inst
Setup an additional local DS instance via a silent file.

Here is a copy of the silent file

[General] 
FullMachineName=snowflakes.example.com 
SuiteSpotUserID=dsuser 
SuiteSpotGroup=dsgroup

[slapd] 
ServerPort=2389 
ServerIdentifier=test-inst2
Suffix=dc=test-inst2,dc=com  
ds_bename = exampleDB
RootDN=cn=Directory Manager 
RootDNPwd=password

setup-ds.pl -s -f /var/tmp/setupds.inf finishes successfully, but register-ds-admin.pl fails to register the test-inst2 interactively:

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If you want to register the server test-inst2, input the Directory Manager password on the server.

If you don't, type return.
[Directory Manager password on test-inst2 or return]:
The map value 'Suffix' for key 'ds_suffix' did not map to a value in any of the given information files.

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