Fix build $CC fallback

Signed-off-by: Graham MacDonald <grahamamacdonald@gmail.com>

util/src/harvey/cmd/build/build.go

@@ -207,23 +207,26 @@ func adjust(s []string) []string {
 // return the given absolute path as an absolute path rooted at the harvey tree.
 func fromRoot(p string) string {
 	expandedPath := os.ExpandEnv(p)
-	if path.IsAbs(p) {
+	if path.IsAbs(expandedPath) {
 		expandedPath = path.Join(harvey, expandedPath)
 	}
 
-	// Travis has versioned CCs of the form clang-X.Y.  We don't want to have
-	// a file for each version of the compilers, so check if the versioned
-	// file exists first.  If it doesn't, fall back to the unversioned file.
-	expandedCc := os.Getenv("CC")
-	expandedCcTokens := strings.Split(expandedCc, "-")
-	fallbackCc := expandedCcTokens[0]
-	if strings.Contains(expandedPath, "$CC") && len(expandedCcTokens) > 1 {
-		if _, err := os.Stat(expandedPath); err != nil {
-			if os.IsNotExist(err) {
-				oldCc := os.Getenv("CC")
-				os.Setenv("CC", fallbackCc)
-				expandedPath = fromRoot(p)
-				os.Setenv("CC", oldCc)
+	if strings.Contains(p, "$CC") {
+		// Travis has versioned CCs of the form clang-X.Y.  We don't want to have
+		// a file for each version of the compilers, so check if the versioned
+		// file exists first.  If it doesn't, fall back to the unversioned file.
+		expandedCc := os.Getenv("CC")
+		expandedCcTokens := strings.Split(expandedCc, "-")
+		fallbackCc := expandedCcTokens[0]
+		//fmt.Printf(">>>CC=%v fallback=%v\n", expandedCc, fallbackCc)
+		if len(expandedCcTokens) > 1 {
+			if _, err := os.Stat(expandedPath); err != nil {
+				if os.IsNotExist(err) {
+					oldCc := os.Getenv("CC")
+					os.Setenv("CC", fallbackCc)
+					expandedPath = fromRoot(p)
+					os.Setenv("CC", oldCc)
+				}
 			}
 		}
 	}