Fix PersonIdent to always use SystemReader

Under unit tests we want the when and timezone to come from the
MockSystemReader and be stable.  We did this for the default
constructor based on the Repository, but failed to do it for the
name,emailAddress variant of the constructor.

Change-Id: I608ac7cf01673729303395e19b379b38fef136b3
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

org.eclipse.jgit/src/org/eclipse/jgit/lib/PersonIdent.java

@@ -99,7 +99,10 @@ public PersonIdent(final PersonIdent pi) {
 	 * @param aEmailAddress
 	 */
 	public PersonIdent(final String aName, final String aEmailAddress) {
-		this(aName, aEmailAddress, new Date(), TimeZone.getDefault());
+		name = aName;
+		emailAddress = aEmailAddress;
+		when = SystemReader.getInstance().getCurrentTime();
+		tzOffset = SystemReader.getInstance().getTimezone(when);
 	}
 
 	/**