Odd behaviour when uploading .svg Assets
Half-bug, half side-effect/undesired behavior for SVG sanitization that got added in Craft 2.6.2982 for SVGs that use embedded data.

The next release of Craft (post 2.6.2983) adds a sanitizeSvgUploads config setting (true by default) that you will be able to set to false to disable SVG sanitization.