[caglarpir]

A GPX that writes its times with two fractions, as 2026-08-12T06:32:05.000.000Z, failed the video as "Stationary video". gpxpy reads no time for a track point whose time it cannot read, and says nothing of it; the GPX reader then left out every point without a time, and _check_video_limits called _is_video_stationary([]), which says True. v0.14.7 does the same.

Path	Before	After
process VIDEO --video_geotag_source gpx (and process_and_upload)	MapillaryStationaryVideoError "Stationary video"	MapillaryInvalidGPXError
video_process VIDEO OUT --geotag_source gpx	MapillaryVideoGPSNotFoundError "No GPS points found"	MapillaryInvalidGPXError
process IMAGES --geotag_source gpx	MapillaryInvalidGPXError "No timestamped points found in the GPX file …"	MapillaryInvalidGPXError, saying why
Half the times unreadable	ready, 30 of 60 points left out silently	ready, with a warning

The messages:

• X.gpx has no track point with a time that can be read: '2026-08-12T06:32:05.000.000Z' is not a GPX time, which looks like 2026-08-12T06:32:05.000Z
• X.gpx has no track point with a time that can be read: its track points have no <time>
• X.gpx has no track points; routes and waypoints are not read
• once per file: Ignoring 30 of the 60 points in the GPX file X, whose times cannot be read (e.g. '2026-08-12T06:32:06.000.000Z')

gpxpy keeps no raw text, so on this path only, the file is read again, as XML, for the track point times that gpxpy rejects. No time is guessed from them. Track points without a <time> are still left out without a word: GPX allows them, and ExifTool writes one only on the points of a GoPro video that have a GPS time.

Commits:

1. The above.
2. Backstop: a video that reaches the checks of process with no points fails as MapillaryVideoGPSNotFoundError "No GPS points found", not as stationary. This also covers an NMEA file without the date of any fix.
3. "X.gpx is not a valid GPX file" gives gpxpy's reason, e.g. Error parsing XML: no element found: line 6, column 85; a GPX cut short said only "not a valid GPX file".

Tests: unit tests for the two-fraction form, no <time>, only routes or waypoints, half the times unreadable, a valid GPX and the before-1980 warning (both unchanged); integration tests for process of a video and of images, and for video_process. Also checked by hand with GPX files made from a dashcam video's own track, through process, video_process, process_and_upload --dry_run and process of images, and on sample videos and GPX files from many cameras.