Google reportedly broke the ADB sideload
functionality for large files like the ones included with the new Pixel
and Nexus in its latest platform tools that were distributed on March
16. Specifically, version rev.25.0.4 has been repurposed to save memory, but in doing so cannot deal with the size of the extracted OTA image files.
The fix is simple: if you’re using ADB, you should download the previous version, rev.25.0.3 released in December, which should fix the problem.