Consolidate path equality checks into pathEqual

Instead of repeating the problem every time, fold this stuff into a
function we can use.

Changelog.md

@@ -1,5 +1,6 @@
-# Unreleased
+# v56 (2016/02/26)
 
+* replace path comparisons with case insensitive pathEqual()
 * add versionString() to debug output
 * Send log output to Stderr
 

list.go

@@ -189,7 +189,7 @@ func findDirForPath(path string, ip *build.Package) (string, error) {
 		debugln("resolving vendor posibilities:", ip.Dir, ip.Root)
 		cr := cleanPath(ip.Root)
 
-		for base := cleanPath(ip.Dir); base != cr; base = cleanPath(filepath.Dir(base)) {
+		for base := cleanPath(ip.Dir); !pathEqual(base, cr); base = cleanPath(filepath.Dir(base)) {
 			s := filepath.Join(base, "vendor", path)
 			debugln("Adding search dir:", s)
 			search = append(search, s)

util.go

@@ -5,6 +5,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"strings"
 )
 
 // Runs a command in dir.
@@ -50,3 +51,10 @@ func driveLetterToUpper(path string) string {
 func cleanPath(path string) string {
 	return driveLetterToUpper(filepath.Clean(path))
 }
+
+// deal with case insensitive filesystems and other weirdness
+func pathEqual(a, b string) bool {
+	a = cleanPath(a)
+	b = cleanPath(b)
+	return strings.EqualFold(a, b)
+}

vcs.go

@@ -125,7 +125,7 @@ func (vf vcsFiles) Contains(path string) bool {
 	// Slow path for case insensitive filesystems
 	// See #310
 	for f := range vf {
-		if strings.EqualFold(f, path) {
+		if pathEqual(f, path) {
 			return true
 		}
 		// git's root command (maybe other vcs as well) resolve symlinks, so try that too
@@ -134,7 +134,7 @@ func (vf vcsFiles) Contains(path string) bool {
 		if err != nil {
 			return false
 		}
-		if strings.EqualFold(f, p) {
+		if pathEqual(f, p) {
 			return true
 		}
 	}
@@ -162,7 +162,7 @@ func (v *VCS) listFiles(dir string) vcsFiles {
 				panic(err) // this should not happen
 			}
 
-			if strings.EqualFold(filepath.Dir(path), dir) {
+			if pathEqual(filepath.Dir(path), dir) {
 				files[path] = true
 			}
 		}

version.go

@@ -5,7 +5,7 @@ import (
 	"runtime"
 )
 
-const version = 55
+const version = 56
 
 var cmdVersion = &Command{
 	Name:  "version",