.lock files show up in directory listings

[RubenVerborgh]

This bug is hard to reproduce timing-wise, but I have received at least one directory listing containing a .lock file.

For reference, this is what it looked like:

@prefix : <#>.
@prefix inbox: <>.
@prefix ldp: <http://www.w3.org/ns/ldp#>.
@prefix terms: <http://purl.org/dc/terms/>.
@prefix XML: <http://www.w3.org/2001/XMLSchema#>.
@prefix dcd: <dcd04010-0722-11eb-aaa1-f5587892eb36.ttl.lock/>.
@prefix st: <http://www.w3.org/ns/posix/stat#>.
@prefix tur: <http://www.w3.org/ns/iana/media-types/text/turtle#>.

inbox:
    a ldp:BasicContainer, ldp:Container;
    terms:modified "2020-10-05T19:22:19Z"^^XML:dateTime;
    ldp:contains
        <378f8150-0728-11eb-aaa1-f5587892eb36.ttl>,
        <4870d3e0-073f-11eb-aaa1-f5587892eb36.ttl>,
        <92f0e640-073e-11eb-aaa1-f5587892eb36.ttl>,
        <abf84aa0-0731-11eb-aaa1-f5587892eb36.ttl>,
        <dcd04010-0722-11eb-aaa1-f5587892eb36.ttl>, dcd:;
    st:mtime 1601925739.707;
    st:size 4096.
<378f8150-0728-11eb-aaa1-f5587892eb36.ttl>
    a tur:Resource, ldp:Resource;
    terms:modified "2020-10-05T16:31:27Z"^^XML:dateTime;
    st:mtime 1601915487.715;
    st:size 531.
<4870d3e0-073f-11eb-aaa1-f5587892eb36.ttl>
    a tur:Resource, ldp:Resource;
    terms:modified "2020-10-05T19:16:34Z"^^XML:dateTime;
    st:mtime 1601925394.459;
    st:size 552.
<92f0e640-073e-11eb-aaa1-f5587892eb36.ttl>
    a tur:Resource, ldp:Resource;
    terms:modified "2020-10-05T19:11:29Z"^^XML:dateTime;
    st:mtime 1601925089.955;
    st:size 552.
<abf84aa0-0731-11eb-aaa1-f5587892eb36.ttl>
    a tur:Resource, ldp:Resource;
    terms:modified "2020-10-05T17:39:08Z"^^XML:dateTime;
    st:mtime 1601919548.486;
    st:size 531.
<dcd04010-0722-11eb-aaa1-f5587892eb36.ttl>
    a tur:Resource, ldp:Resource;
    terms:modified "2020-10-05T15:53:07Z"^^XML:dateTime;
    st:mtime 1601913187.983;
    st:size 531.
dcd:
    a ldp:BasicContainer, ldp:Container, ldp:Resource;
    terms:modified "2020-10-05T19:22:19Z"^^XML:dateTime;
    st:mtime 1601925739.711;
    st:size 4096.

Note how it ends with .lock/ as opposed to just .lock, which might be the reason why it is not caught.

Should be fixed when not using on-disk locking anymore (#1475), but wanted to mention this in case there would be issues with other magic extensions.

[csarven]

Related to #1751