Possibly another symptom of issue #3917...
This is error is occurring reliably for me using serf trunk@1489 and subversion
trunk@1137005
>svn export -q https://svn.apache.org/repos/asf/subversion/trunk
s.a.o.subversion.trunk.export
..\..\..\subversion\svn\export-cmd.c:123: (apr_err=730014)
..\..\..\subversion\libsvn_client\export.c:1068: (apr_err=730014)
..\..\..\subversion\libsvn_client\ra.c:464: (apr_err=730014)
..\..\..\subversion\libsvn_client\ra.c:324: (apr_err=730014)
..\..\..\subversion\libsvn_ra\ra_loader.c:496: (apr_err=730014)
..\..\..\subversion\libsvn_ra\ra_loader.c:496: (apr_err=730014)
svn: E730014: Unable to connect to a repository at URL
'https://svn.apache.org/repos/asf/subversion/trunk'
..\..\..\subversion\libsvn_ra_serf\util.c:684: (apr_err=730014)
svn: E730014: Error running context: The system detected an invalid pointer
address in attempting to use a pointer argument in a call.
This works with ra_neon.