This bug is created as a clone of upstream ticket:
https://fedorahosted.org/389/ticket/49092

Note: found in debugging/testing ticket 47973.

Steps:

cat > /path/to/99user.ldif << EOF
dn: cn=schema
attributetypes: ( 8.9.10.11.12.13.14 NAME 'MozillaAttribute' SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 X-ORIGIN 'Mozilla Dummy Schema' )
objectclasses: ( 1.2.3.4.5.6.7 NAME 'MozillaObject' SUP top MUST ( objectclass $ cn ) MAY ( givenName $ sn $ MozillaAttribute ) X-ORIGIN 'user defined' )
EOF

schema-reload.pl -Z SERVERINST -D 'cn=directory manager' -W
<== expect to success

ldapsearch returns, e.g. "MAY ( givenName $ sn $ MozillaAttribute )"

cat > /path/to/98user.ldif << EOF
dn: cn=schema
attributetypes: ( 8.9.10.11.12.13.140 NAME 'MozillaAttribute' SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 X-ORIGIN 'Mozilla Dummy Schema' )
objectclasses: ( 1.2.3.4.5.6.70 NAME 'MoZiLLaOBJeCT' SUP top MUST ( objectclass $ cn ) MAY ( givenName $ sn $ MoZiLLaATTRiBuTe ) X-ORIGIN 'user defined' )
EOF
Note: the objectclasses and attributetypes have different OIDs.

schema-reload.pl -Z SERVERINST -D 'cn=directory manager' -W
<== expect to fail.  check it in the error log.

Although the reload failed, ldapsearch returns, e.g. 1.2.3.4.5.6.70 and "MAY ( givenName $ sn $ MoZiLLaATTRiBuTe )"

If you try to restart the server, it refuses to start due to the invalid schema.

The problem is observed on rhel6 as well as on the local build from the master branch.