update winrmcp vendor and update error message in file provisioner to aid user who messes up file path name. update file provisioner docs

provisioner/file/provisioner.go

@@ -185,6 +185,11 @@ func (p *Provisioner) ProvisionUpload(ui packer.Ui, comm packer.Communicator) er
 
 		// Upload the file
 		if err = comm.Upload(dst, pf, &fi); err != nil {
+			if strings.Contains(err.Error(), "Error restoring file") {
+				ui.Error(fmt.Sprintf("Upload failed: %s; this can occur when "+
+					"your file destination is a folder without a trailing "+
+					"slash.", err))
+			}
 			ui.Error(fmt.Sprintf("Upload failed: %s", err))
 			return err
 		}

vendor/github.com/packer-community/winrmcp/winrmcp/cp.go

@@ -117,7 +117,11 @@ func restoreContent(client *winrm.Client, fromPath, toPath string) error {
 		$tmp_file_path = [System.IO.Path]::GetFullPath("%s")
 		$dest_file_path = [System.IO.Path]::GetFullPath("%s".Trim("'"))
 		if (Test-Path $dest_file_path) {
-			rm $dest_file_path
+			if (Test-Path -Path $dest_file_path -PathType container) {
+				Exit 1
+			} else {
+				rm $dest_file_path
+			}
 		}
 		else {
 			$dest_dir = ([System.IO.Path]::GetDirectoryName($dest_file_path))

vendor/vendor.json

@@ -1321,10 +1321,10 @@
 			"versionExact": "v2.0.0"
 		},
 		{
-			"checksumSHA1": "/NoE6t3UkW4/iKAtbf59GGv6tF8=",
+			"checksumSHA1": "qDOL2Q0BzBA5WwQN06a5/MbEGFQ=",
 			"path": "github.com/packer-community/winrmcp/winrmcp",
-			"revision": "81144009af586de8e7729b829266f09dd0d59701",
-			"revisionTime": "2018-01-02T16:08:24Z"
+			"revision": "0fd363d6159ae26cd0be16262941301e69461641",
+			"revisionTime": "2018-09-21T17:45:48Z"
 		},
 		{
 			"checksumSHA1": "oaXvjFg802gS/wx1bx2gAQwa7XQ=",

website/source/docs/provisioners/file.html.md

@@ -44,7 +44,11 @@ The available configuration options are listed below.
 
 -   `destination` (string) - The path where the file will be uploaded to in
     the machine. This value must be a writable location and any parent
-    directories must already exist.
+    directories must already exist. If the source is a file, it's a good idea to
+    make the destination a file as well, but if you set your destination as a
+    directory, at least make sure that the destination ends in a trailing slash
+    so that Packer knows to use the source's basename in the final upload path.
+    Failure to do so may cause Packer to fail on file uploads.
 
 -   `direction` (string) - The direction of the file transfer. This defaults to
     "upload". If it is set to "download" then the file "source" in the machine