Refresh git configuration before looking for the tracking branch.

Author: alanjrogers

Classes/GTBranch.m

@@ -27,6 +27,7 @@
 #import "GTReference.h"
 #import "GTEnumerator.h"
 #import "GTRepository.h"
+#import "GTConfiguration.h"
 #import "GTCommit.h"
 #import "GTRemote.h"
 #import "NSError+Git.h"
@@ -175,6 +176,19 @@ - (GTBranch *)trackingBranchWithError:(NSError **)error success:(BOOL *)success
 		return self;
 	}
 
+	// Refresh configuration first so that libgit2 gets any updated tracking
+	// refs in the repository's config.
+	GTConfiguration *configuration = [self.repository configurationWithError:error];
+	if (configuration == nil) {
+		if (success != NULL) *success = NO;
+		return nil;
+	}
+
+	if (![configuration refresh:error]) {
+		if (success != NULL) *success = NO;
+		return nil;
+	}
+
 	git_reference *trackingRef = NULL;
 	int gitError = git_branch_upstream(&trackingRef, self.reference.git_reference);