bad local file timestamp on undo checkout

[jt]

sos v4.1.2, using file modification times option

check out a file
modify it (timestamp is now; the A bit is set - ok)
undo check out

=> you get the server version of the file, BUT the timestamp is still now and the RA bits are set

expect:
- file should have the modification timestamp of the server file, not the edit timestamp of the file being replaced!
- A bit should be cleared