Unpredictable results when doing msQueryBy***() on WFS layers

[ahocevar@…]

When performing a query, eg. msQueryByPoint() on a WFS layer (info: SRS is
different than SRS of the map), one of the following happens:

- PHP-Mapscript throws a fatal error: No matching record(s) found. This happens
when I click on a single WFS feature in the map.

- A result for one or two features is returned: This happens when I click on a
bunch of dozens of features.

The expected result would be to get exactly the features within the tolerance of
my click.

Please see the example layer definition of my Mapfile below. The WFS URI works:

LAYER
  NAME "documentation"
  TYPE POINT
  STATUS ON
  CONNECTIONTYPE WFS
  CONNECTION "http://85.10.210.46:8989/geoserver/wfs?"
  METADATA
    "wfs_typename"          "disalp:documentation"
    "wfs_version"           "1.0.0"
    "wfs_request_method"    "GET"
    "wfs_connectiontimeout" "60"
  END
  PROJECTION
  "init=epsg:4326"
  END
  CLASS
    SYMBOL "square"
    COLOR 255 255 0
    OUTLINECOLOR 0 0 0
    SIZE 15
    TEMPLATE "template.html"
  END
END