Bugfix: obj.realSha() in history.js returns nil/undefined more often than not.

My guess is that this is caused by the rather large buffer size of 2000. 
Since we know that a full SHA will never be longer than 40+1 bytes, we simply use 
a default define from libgit2 for the buffer size.

Author: andreberg

PBGitCommit.m

@@ -26,8 +26,8 @@ - (NSArray *) parents
 	NSMutableArray *p = [NSMutableArray arrayWithCapacity:nParents];
 	for (i = 0; i < nParents; ++i)
 	{
-		char buff[2000];
-		char * s = git_oid_to_string(buff, 2000, parentShas + i);		
+		char buff[GIT_OID_HEXSZ+1];
+		char * s = git_oid_to_string(buff, GIT_OID_HEXSZ+1, parentShas + i);		
 		[p addObject:[NSString stringWithUTF8String:s]];
 	}
 	return p;
@@ -127,8 +127,8 @@ - (git_oid *)sha
 - (NSString *)realSha
 {
 	if (!realSHA) {
-		char buff[2000];
-		char * hex = git_oid_to_string(buff, 2000, &sha);		
+		char buff[GIT_OID_HEXSZ+1];
+		char * hex = git_oid_to_string(buff, GIT_OID_HEXSZ+1, &sha);		
 		realSHA = [NSString stringWithUTF8String:hex];
 	}
 

html/views/history/history.js

@@ -7,8 +7,8 @@ var Commit = function(obj) {
 
 	this.refs = obj.refs();
 	this.author_name = obj.author;
-	this.sha = obj.realSha();
-	this.parents = obj.parents;
+    this.sha = obj.realSha();
+    this.parents = obj.parents;
 	this.subject = obj.subject;
 	this.notificationID = null;