Comment 5 for bug 1386838

As LAZA mentioned, you can work around this by adding a character to the filename, and then renaming back to the changed case version you wanted. It will stick, because FAT32 stores the filename case even though it ignores the case when searching for a file.

Note however that even the shell 'mv' command wont let you directly do this without renaming twice. This is because it checks if the destination filename already exists before renaming, and because case is ignored, it does exist. So the rename fails.