fixes rstudio#306: remove the possible trailing slash under Windows

the cause:

normalize('foo',  '/') => C:/foo
normalize('foo/', '/') => C:/foo/

under Windows. For unix, the trailing slash will always be removed in normalizePath()

Author: yihui

NEWS

@@ -126,6 +126,9 @@ shiny 0.8.0.99
   e.g. the label in sliderInput(..., label = HTML('<em>A Label</em>')) will
   not be escaped any more. (#119)
 
+* Fixed #306: the trailing slash in a path could fail `addResourcePath()`
+  under Windows. (Thanks, ZJ Dai)
+
 shiny 0.8.0
 --------------------------------------------------------------------------------
 

R/shiny.R

@@ -674,6 +674,8 @@ resolve <- function(dir, relpath) {
     return(NULL)
   abs.path <- normalizePath(abs.path, winslash='/', mustWork=TRUE)
   dir <- normalizePath(dir, winslash='/', mustWork=TRUE)
+  # trim the possible trailing slash under Windows (#306)
+  if (.Platform$OS.type == 'windows') dir <- sub('/$', '', dir)
   if (nchar(abs.path) <= nchar(dir) + 1)
     return(NULL)
   if (substr(abs.path, 1, nchar(dir)) != dir ||