facet.mincount ignored in range faceting using distributed search

While I was trying to do a range faceting with gap +1YEAR using shards, I noticed that facet.mincount parameter seems to be ignored.

Issue can be reproduced in this way:
Create 2 cores "testshard1" and "testshard2" with:

solrconfig.xml
<?xml version="1.0" encoding="UTF-8" ?>
<config>
<luceneMatchVersion>LUCENE_41</luceneMatchVersion>
<lib dir="/opt/solr/dist" regex="solr-cell-.*\.jar"/>
<directoryFactory name="DirectoryFactory" class="${solr.directoryFactory:solr.NRTCachingDirectoryFactory}"/>
<updateHandler class="solr.DirectUpdateHandler2" />
<requestHandler name="/select" class="solr.SearchHandler">
<lst name="defaults">
<str name="echoParams">explicit</str>
<int name="rows">10</int>
<str name="df">id</str>
</lst>
</requestHandler>
<requestHandler name="/update" class="solr.UpdateRequestHandler" />
<requestHandler name="/admin/" class="org.apache.solr.handler.admin.AdminHandlers" />
<requestHandler name="/admin/ping" class="solr.PingRequestHandler">
<lst name="invariants">
<str name="q">solrpingquery</str>
</lst>
<lst name="defaults">
<str name="echoParams">all</str>
</lst>
</requestHandler>
</config>

schema.xml
<?xml version="1.0" ?>
<schema name="${solr.core.name}" version="1.5" xmlns:xi="http://www.w3.org/2001/XInclude">
<fieldType name="int" class="solr.TrieIntField" precisionStep="0" positionIncrementGap="0"/>
<fieldType name="long" class="solr.TrieLongField" precisionStep="0" positionIncrementGap="0"/>
<fieldType name="date" class="solr.TrieDateField" precisionStep="0" positionIncrementGap="0"/>
<field name="version" type="long" indexed="true" stored="true"/>
<field name="id" type="int" indexed="true" stored="true" multiValued="false" />
<field name="date" type="date" indexed="true" stored="true" multiValued="false" />
<uniqueKey>id</uniqueKey>
<defaultSearchField>id</defaultSearchField>
</schema>

Insert in testshard1:
<add>
<doc>
<field name="id">1</field>
<field name="date">2014-06-20T12:51:00Z</field>
</doc>
</add>

Insert into testshard2:
<add>
<doc>
<field name="id">2</field>
<field name="date">2013-06-20T12:51:00Z</field>
</doc>
</add>

Now if I execute:

curl "http://localhost:8983/solr/testshard1/select?q=id:1&facet=true&facet.mincount=1&facet.range=date&f.date.facet.range.start=1900-01-01T00:00:00Z&f.date.facet.range.end=NOW&f.date.facet.range.gap=%2B1YEAR&shards=localhost%3A8983%2Fsolr%2Ftestshard1%2Clocalhost%3A8983%2Fsolr%2Ftestshard2&shards.info=true&wt=json"

I obtain:
{"responseHeader":{"status":0,"QTime":88,"params":{"f.date.facet.range.gap":"+1YEAR","f.date.facet.range.start":"1900-01-01T00:00:00Z","facet":"true","shards":"localhost:8983/solr/testshard1,localhost:8983/solr/testshard2","facet.mincount":"1","q":"id:1","shards.info":"true","facet.range":"date","wt":"json","f.date.facet.range.end":"NOW"}},"shards.info":{"localhost:8983/solr/testshard2":

{"numFound":0,"maxScore":0.0,"shardAddress":"http://localhost:8983/solr/testshard2","time":76}

,"localhost:8983/solr/testshard1":{"numFound":1,"maxScore":0.30685282,"shardAddress":"http://localhost:8983/solr/testshard1","time":79}},"response":{"numFound":1,"start":0,"maxScore":0.30685282,"docs":[

{"id":1,"date":"2014-06-20T12:51:00Z"}

]},"facet_counts":{"facet_queries":{},"facet_fields":{},"facet_dates":{},"facet_ranges":{"date":{"counts":["1900-01-01T00:00:00Z",0,"1901-01-01T00:00:00Z",0,"1902-01-01T00:00:00Z",0,"1903-01-01T00:00:00Z",0,"1904-01-01T00:00:00Z",0,"1905-01-01T00:00:00Z",0,"1906-01-01T00:00:00Z",0,"1907-01-01T00:00:00Z",0,"1908-01-01T00:00:00Z",0,"1909-01-01T00:00:00Z",0,"1910-01-01T00:00:00Z",0,"1911-01-01T00:00:00Z",0,"1912-01-01T00:00:00Z",0,"1913-01-01T00:00:00Z",0,"1914-01-01T00:00:00Z",0,"1915-01-01T00:00:00Z",0,"1916-01-01T00:00:00Z",0,"1917-01-01T00:00:00Z",0,"1918-01-01T00:00:00Z",0,"1919-01-01T00:00:00Z",0,"1920-01-01T00:00:00Z",0,"1921-01-01T00:00:00Z",0,"1922-01-01T00:00:00Z",0,"1923-01-01T00:00:00Z",0,"1924-01-01T00:00:00Z",0,"1925-01-01T00:00:00Z",0,"1926-01-01T00:00:00Z",0,"1927-01-01T00:00:00Z",0,"1928-01-01T00:00:00Z",0,"1929-01-01T00:00:00Z",0,"1930-01-01T00:00:00Z",0,"1931-01-01T00:00:00Z",0,"1932-01-01T00:00:00Z",0,"1933-01-01T00:00:00Z",0,"1934-01-01T00:00:00Z",0,"1935-01-01T00:00:00Z",0,"1936-01-01T00:00:00Z",0,"1937-01-01T00:00:00Z",0,"1938-01-01T00:00:00Z",0,"1939-01-01T00:00:00Z",0,"1940-01-01T00:00:00Z",0,"1941-01-01T00:00:00Z",0,"1942-01-01T00:00:00Z",0,"1943-01-01T00:00:00Z",0,"1944-01-01T00:00:00Z",0,"1945-01-01T00:00:00Z",0,"1946-01-01T00:00:00Z",0,"1947-01-01T00:00:00Z",0,"1948-01-01T00:00:00Z",0,"1949-01-01T00:00:00Z",0,"1950-01-01T00:00:00Z",0,"1951-01-01T00:00:00Z",0,"1952-01-01T00:00:00Z",0,"1953-01-01T00:00:00Z",0,"1954-01-01T00:00:00Z",0,"1955-01-01T00:00:00Z",0,"1956-01-01T00:00:00Z",0,"1957-01-01T00:00:00Z",0,"1958-01-01T00:00:00Z",0,"1959-01-01T00:00:00Z",0,"1960-01-01T00:00:00Z",0,"1961-01-01T00:00:00Z",0,"1962-01-01T00:00:00Z",0,"1963-01-01T00:00:00Z",0,"1964-01-01T00:00:00Z",0,"1965-01-01T00:00:00Z",0,"1966-01-01T00:00:00Z",0,"1967-01-01T00:00:00Z",0,"1968-01-01T00:00:00Z",0,"1969-01-01T00:00:00Z",0,"1970-01-01T00:00:00Z",0,"1971-01-01T00:00:00Z",0,"1972-01-01T00:00:00Z",0,"1973-01-01T00:00:00Z",0,"1974-01-01T00:00:00Z",0,"1975-01-01T00:00:00Z",0,"1976-01-01T00:00:00Z",0,"1977-01-01T00:00:00Z",0,"1978-01-01T00:00:00Z",0,"1979-01-01T00:00:00Z",0,"1980-01-01T00:00:00Z",0,"1981-01-01T00:00:00Z",0,"1982-01-01T00:00:00Z",0,"1983-01-01T00:00:00Z",0,"1984-01-01T00:00:00Z",0,"1985-01-01T00:00:00Z",0,"1986-01-01T00:00:00Z",0,"1987-01-01T00:00:00Z",0,"1988-01-01T00:00:00Z",0,"1989-01-01T00:00:00Z",0,"1990-01-01T00:00:00Z",0,"1991-01-01T00:00:00Z",0,"1992-01-01T00:00:00Z",0,"1993-01-01T00:00:00Z",0,"1994-01-01T00:00:00Z",0,"1995-01-01T00:00:00Z",0,"1996-01-01T00:00:00Z",0,"1997-01-01T00:00:00Z",0,"1998-01-01T00:00:00Z",0,"1999-01-01T00:00:00Z",0,"2000-01-01T00:00:00Z",0,"2001-01-01T00:00:00Z",0,"2002-01-01T00:00:00Z",0,"2003-01-01T00:00:00Z",0,"2004-01-01T00:00:00Z",0,"2005-01-01T00:00:00Z",0,"2006-01-01T00:00:00Z",0,"2007-01-01T00:00:00Z",0,"2008-01-01T00:00:00Z",0,"2009-01-01T00:00:00Z",0,"2010-01-01T00:00:00Z",0,"2011-01-01T00:00:00Z",0,"2012-01-01T00:00:00Z",0,"2013-01-01T00:00:00Z",0,"2014-01-01T00:00:00Z",1],"gap":"+1YEAR","start":"1900-01-01T00:00:00Z","end":"2015-01-01T00:00:00Z"}}}}

though facet.mincount is set to 1.