Fix mergeBranchIntoCurrentBranch for conflicted state

checkout_opts passed to libgit2 missed a GIT_CHECKOUT_SAFE strategy, causing a dry run and only conflicted files being written out to the tree (losing all other non-conflicted ones).

Author: slavikus

ObjectiveGit/GTRepository+Merging.m

@@ -139,7 +139,7 @@ - (BOOL)mergeBranchIntoCurrentBranch:(GTBranch *)branch withError:(NSError **)er
 			// Write conflicts
 			git_merge_options merge_opts = GIT_MERGE_OPTIONS_INIT;
 			git_checkout_options checkout_opts = GIT_CHECKOUT_OPTIONS_INIT;
-			checkout_opts.checkout_strategy = GIT_CHECKOUT_ALLOW_CONFLICTS;
+			checkout_opts.checkout_strategy = (GIT_CHECKOUT_SAFE | GIT_CHECKOUT_ALLOW_CONFLICTS);
 
 			git_annotated_commit *annotatedCommit;
 			[self annotatedCommit:&annotatedCommit fromCommit:remoteCommit error:error];