Revert "lib/model: Handle filename conflicts on Windows."

This reverts commit 01e50eb3fa.

lib/model/rwfolder.go

@@ -435,13 +435,6 @@ func (f *sendReceiveFolder) pullerIteration(ignores *ignore.Matcher) int {
 			continue
 		}
 
-		// Verify that we handle the right thing and not something whose name
-		// collides.
-		if !osutil.CheckNameConflict(f.dir, fi.Name) {
-			f.newError(fi.Name, errNameConflict)
-			continue
-		}
-
 		switch {
 		case fi.IsDeleted():
 			// A deleted file, directory or symlink
@@ -531,13 +524,6 @@ nextFile:
 			continue
 		}
 
-		// Verify that we handle the right thing and not something whose name
-		// collides.
-		if !osutil.CheckNameConflict(f.dir, fi.Name) {
-			f.newError(fi.Name, errNameConflict)
-			continue
-		}
-
 		// Check our list of files to be removed for a match, in which case
 		// we can just do a rename instead.
 		key := string(fi.Blocks[0].Hash)
@@ -1287,16 +1273,6 @@ func (f *sendReceiveFolder) copierRoutine(in <-chan copyBlocksState, pullChan ch
 					if err != nil {
 						return false
 					}
-					// The following checks are racy
-					if !osutil.IsDir(folderRoots[folder], filepath.Dir(file)) {
-						return false
-					}
-					if !osutil.CheckNameConflict(folderRoots[folder], file) {
-						return false
-					}
-					if info, err := osutil.Lstat(inFile); err != nil || !info.Mode().IsRegular() {
-						return false
-					}
 					fd, err := os.Open(inFile)
 					if err != nil {
 						return false