Operating system: Xubuntu 17.10
GPU: Nvidia Geforce GTX760
Broken: 2.79, 2.79a, 2.80
**Short description of error**
Blender does not detect correctly MKV videos length.
This seven and a half minutes [MKV video](https://drive.google.com/open?id=1UVdBwJev7RnEAurNRT0UNvIgU2VEZ0Gi) is imported as having over 400k frames.
Hard to describe by words, so I've made the video: https://youtu.be/rJbKQp4yle4
This problem is observed both in 2.79 and in 2.79a release candidate. The problem does not depend on render engine selected.