Fix "--config" rejecting directories with a "."

Fixes fsprojects#694

src/Fantomas.Tests/FormatConfigJsonConfigurationFileTests.fs

@@ -91,6 +91,34 @@ let ``pointing to config in a subfolder should return parent config file as well
         delete parentFile
         delete childFolder
 
+[<Test>]
+let ``pointing to subfolder containing dot and trailing slash returns parent config file`` () =
+    let parentFile = mkConfig None FormatConfig.Default
+    let subDir = uniqueString() + ".dir"
+    mkConfigFromContent "Test.fs" (Some(subDir)) "" |> ignore
+    let dirSep = string Path.DirectorySeparatorChar
+    let childFolder = Path.GetDirectoryName(parentFile) + dirSep + subDir + dirSep
+    try
+        let paths = ConfigFile.findConfigurationFiles childFolder
+        paths == [parentFile]
+    finally
+        delete parentFile
+        delete childFolder
+
+[<Test>]
+let ``pointing to subfolder conntaining dot without trailing slash returns parent config file`` () =
+    let parentFile = mkConfig None FormatConfig.Default
+    let subDir = uniqueString() + ".dir"
+    mkConfigFromContent "Test.fs" (Some(subDir)) "" |> ignore
+    let dirSep = string Path.DirectorySeparatorChar
+    let childFolder = Path.GetDirectoryName(parentFile) + dirSep + subDir
+    try
+        let paths = ConfigFile.findConfigurationFiles childFolder
+        paths == [parentFile]
+    finally
+        delete parentFile
+        delete childFolder
+
 [<Test>]
 let ``simple config file parses valid option`` () =
     let path = mkConfigFromJson None "{\"KeepNewlineAfter\":true}"

src/Fantomas/ConfigFile.fs

@@ -23,7 +23,7 @@ let rec findConfigurationFiles fileOrFolder : string list =
         |> List.map (fun fn -> Path.Combine(folderPath, fn))
         |> List.filter (File.Exists)
 
-    if Path.GetExtension(fileOrFolder) = "" && Directory.Exists fileOrFolder then
+    if Directory.Exists fileOrFolder then
         getParentFolders [] fileOrFolder
         |> List.collect findConfigInFolder
     elif File.Exists(fileOrFolder) then