When Directory.GetCurrentDirectory() == '/' on a Unix system, Path.GetFullPath("test.txt") return "//test.txt". Simple check needs to be added to see if the current directory ends in a DirectorySeparatorStr.
This appears to have been open for a while. Is this fix being merged or rejected?
I'm looking into it. So far I've reproduced the issue with a test case and confirmed your suggested fix fixes the original issue.
Reading the Github thread, it seems there were also some issues on Windows? I wanted to check that first before getting this in.
Thanks for the bug report and sorry for the long wait on getting this processed.
Fixed by https://github.com/mono/mono/commit/1bff9d890f95e72e4145d48980a05908c87b53ce.