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Pretty fine, but surfaces with surfceparm playerclip (even standalone) seem being recognized as non solid too.
Can you provide a test map to show the problem.
Its compiled with -patchmeta, can see normal behavior compiling it without one.
With -patchmeta solid patches are saved in bsp to save collisions; nonsolid are deleted as not needed.
Playerclipped are deleted too (by mistake).
Looks like this flag also sets surfaceparm trans automatically. Its fine for usual usage of invisible playerclip. Not fine, if you want shadow.