Do not read ~/.gitconfig during JUnit tests

index 259bc05..4b5314c 100644
@@ -128,12 +128,10 @@ public void test007_readUserInfos() throws IOException {
 			hostname = "localhost";
 		}
 
-		final File globalConfig = writeTrashFile("global.config", "");
 		final File localConfig = writeTrashFile("local.config", "");
 		System.clearProperty(Constants.OS_USER_NAME_KEY);
 
-		RepositoryConfig globalRepositoryConfig = new RepositoryConfig(null, globalConfig);
-		RepositoryConfig localRepositoryConfig = new RepositoryConfig(globalRepositoryConfig, localConfig);
+		RepositoryConfig localRepositoryConfig = new RepositoryConfig(userGitConfig, localConfig);
 		fakeSystemReader.values.clear();
 
 		String authorName;

@@ -164,8 +162,8 @@ public void test007_readUserInfos() throws IOException {
 		assertEquals("author@email", authorEmail);
 
 		// the values are defined in the global configuration
-		globalRepositoryConfig.setString("user", null, "name", "global username");
-		globalRepositoryConfig.setString("user", null, "email", "author@globalemail");
+		userGitConfig.setString("user", null, "name", "global username");
+		userGitConfig.setString("user", null, "email", "author@globalemail");
 		authorName = localRepositoryConfig.getAuthorName();
 		authorEmail = localRepositoryConfig.getAuthorEmail();
 		assertEquals("global username", authorName);

index 5d8c056..588daf4 100644
@@ -89,12 +89,19 @@
 
 	protected static class FakeSystemReader implements SystemReader {
 		Map<String, String> values = new HashMap<String, String>();
+		RepositoryConfig userGitConfig;
 		public String getenv(String variable) {
 			return values.get(variable);
 		}
 		public String getProperty(String key) {
 			return values.get(key);
 		}
+		public RepositoryConfig openUserConfig() {
+			return userGitConfig;
+		}
+		public void setUserGitConfig(RepositoryConfig userGitConfig) {
+			this.userGitConfig = userGitConfig;
+		}
 	}
 
 	/**

@@ -227,6 +234,13 @@ protected static void checkFile(File f, final String checkData)
 	}
 
 	protected Repository db;
+
+	/**
+	 * mock user's global configuration used instead ~/.gitconfig.
+	 * This configuration can be modified by the tests without any
+	 * effect for ~/.gitconfig.
+	 */
+	protected RepositoryConfig userGitConfig;
 	private static Thread shutdownhook;
 	private static List<Runnable> shutDownCleanups = new ArrayList<Runnable>();
 	private static int testcount;

@@ -257,6 +271,11 @@ public void run() {
 			};
 			Runtime.getRuntime().addShutdownHook(shutdownhook);
 		}
+
+		final File userGitConfigFile = new File(trash_git, "usergitconfig").getAbsoluteFile();
+		userGitConfig = new RepositoryConfig(null, userGitConfigFile);
+		fakeSystemReader.setUserGitConfig(userGitConfig);
+
 		db = new Repository(trash_git);
 		db.create();
 

index 8d19c1b..87fc254 100644
@@ -73,12 +73,12 @@
 public class RepositoryConfig {
 	/**
 	 * Obtain a new configuration instance for ~/.gitconfig.
-	 * 
+	 *
 	 * @return a new configuration instance to read the user's global
 	 *         configuration file from their home directory.
 	 */
 	public static RepositoryConfig openUserConfig() {
-		return new RepositoryConfig(null, new File(FS.userHome(), ".gitconfig"));
+		return systemReader.openUserConfig();
 	}
 
 	private final RepositoryConfig baseConfig;

@@ -113,6 +113,9 @@ public String getenv(String variable) {
 		public String getProperty(String key) {
 			return System.getProperty(key);
 		}
+		public RepositoryConfig openUserConfig() {
+			return new RepositoryConfig(null, new File(FS.userHome(), ".gitconfig"));
+		}
 	};
 
 	RepositoryConfig(final Repository repo) {

index 9187504..32c2e20 100644
@@ -37,11 +37,14 @@
 
 package org.spearce.jgit.util;
 
+import org.spearce.jgit.lib.RepositoryConfig;
+
 /**
  * Interface to read values from the system.
  * <p>
  * When writing unit tests, extending this interface with a custom class
- * permits to simulate an access to a system variable or property.
+ * permits to simulate an access to a system variable or property and
+ * permits to control the user's global configuration.
  * </p>
  */
 public interface SystemReader {

@@ -56,4 +59,9 @@
 	 * @return value of the system property
 	 */
 	String getProperty(String key);
+
+	/**
+	 * @return the git configuration found in the user home
+	 */
+	RepositoryConfig openUserConfig();
 }