Long-standing problem in one of the corner cases of rename(2):
If we rename a directory a check is performed to see if newpath is
identical to oldpath or a subdir of oldpath. This check is
(accidentally? no hints anywhere in ChangeLogs or code) performed
case-insensitive for as long as we use Unicode paths and NT functions.
This leads to the problems described in
https://cygwin.com/ml/cygwin/2016-09/msg00264.html
Change this to be conditional case-sensitive as all other checks but
let's take this with a grain of salt. There may be corner-cases in
this corner-case which require to chek parts of the path always
case-insensitive. Off the top of my head I can't construct such a
case but that's no proof they don't exist :}
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
e3ccb68610