RunCommandLogs: identify and access via uuid

Using a sha1 of the command combined with the build ID is not a
particularly good or unique identifier:

* A build could fail, be restarted, and then succeed -- assuming no
configuration changes, the sha1 hash of the command as well as the build
ID will be the same. This would lead to an overwritten log file.

* Allowing user input to influence filenames is not the best of ideas.

src/lib/Hydra/Schema/Result/RunCommandLogs.pm

@@ -175,8 +175,6 @@ __PACKAGE__->belongs_to(
 
 use POSIX qw(WEXITSTATUS WIFEXITED WIFSIGNALED WTERMSIG);
 use UUID4::Tiny qw(create_uuid_string);
-use Digest::SHA1 qw(sha1_hex);
-use Hydra::Model::DB;
 
 
 =head2 new
@@ -366,29 +364,3 @@ sub did_fail_with_exec_error {
 }
 
 1;
-
-=head2 log_relative_url
-
-Returns the URL to the log file relative to the build it belongs to.
-
-Return:
-
-* The relative URL if a log file exists
-* An empty string otherwise
-=cut
-sub log_relative_url() {
-    my ($self) = @_;
-
-    # Do not return a URL when there is no build yet
-    if (not defined($self->start_time)) {
-      return "";
-    }
-
-    my $sha = sha1_hex($self->command);
-    # Do not return a URL when there is no log file yet
-    if (not -f Hydra::Model::DB::getHydraPath . "/runcommand-logs/" . substr($sha, 0, 2) . "/$sha-" . $self->build_id) {
-        return "";
-    }
-
-    return "runcommand-log/$sha";
-}