throw exception when trying to init a root branch

GitTfs.VsCommon/TfsHelper.PostVs2010.Common.cs

@@ -52,6 +52,13 @@ public override int GetRootChangesetForBranch(string tfsPathBranchToCreate, stri
                     Trace.WriteLine("error: TFS branches "+ tfsPathBranchToCreate +" not found!");
                     return -1;
                 }
+
+                if (tfsBranchToCreate.Properties.ParentBranch == null)
+                {
+                    throw new GitTfsException("error : the branch you try to init '" + tfsPathBranchToCreate + "' is a root branch (e.g. has no parents).",
+                        new List<string> { "Clone this branch from Tfs instead of trying to init it!\n   Command: git tfs clone " + Url + " " + tfsPathBranchToCreate });
+                }
+
                 tfsPathParentBranch = tfsBranchToCreate.Properties.ParentBranch.Item;
                 Trace.WriteLine("Found parent branch : " + tfsPathParentBranch);
 

doc/commands/branch.md

@@ -90,7 +90,11 @@ You should have done (to clone only the trunk) :
 
     git tfs clone http://tfs:8080/tfs/DefaultCollection $/Repository/ProjectTrunk
 
+Note : It is highly recommanded to clone the root branch ( the branch that has no parents, here $/Repository/ProjectTrunk ) to be able to init the other branches after.
+If you clone the branch $/Repository/ProjectBranch, you will never able to init the root branch $/Repository/ProjectTrunk after.
+
 Then use `branch` like this :
+
 ### Init a TFS branches using auto-naming of your git branch
     git tfs branch --init $/Repository/ProjectBranch
 

doc/commands/clone.md

@@ -34,10 +34,21 @@ into a new directory `Project1`, do this:
     git tfs clone http://tfs:8080/tfs/DefaultCollection $/Project1
 
 ### Clone only the trunk (or a branch)
-Sometimes, it could be interesting to clone only a branch of a TFS repository (for exemple to extract only the trunk of your project and manage branches with `[branch](branch.md)`. Then, do this (the clone will be done in the `MyProject1Directory` directory):
+Sometimes, it could be interesting to clone only a branch of a TFS repository (for exemple to extract only the trunk of your project and manage branches with `[branch](branch.md)`. 
+
+Suppose you have on TFS:
+
+    A <- B <- C <- D <- E  $/Project1/Trunk
+               \                              
+                M <- N     $/Project1/Branch
+
+Then, do this (the clone will be done in the `MyProject1Directory` directory):
 
     git tfs clone http://tfs:8080/tfs/DefaultCollection $/Project1/Trunk MyProject1Directory
 
+Note : It is highly recommanded to clone the root branch ( the branch that has no parents, here $/Project1/Trunk ) to be able to init the other branches after.
+If you clone the branch $/Project1/Branch, you will never able to init the root branch $/Project1/Trunk after.
+
 ### What repository path to clone?
 
 If you don't know exactly what repository path to clone, see [list-remote-branches](list-remote-branches.md) command to get a list of the existing repositories.

doc/commands/init-branch.md

@@ -16,6 +16,7 @@ To use this command, you should have cloned only the trunk folder in TFS (and no
                                  (TFS 2008 only! And required!!) ex: $/Repository/ProjectParentBranch
       -u, --username=VALUE       TFS username
       -p, --password=VALUE       TFS password
+
 ## Examples
 
 Suppose you have on TFS:
@@ -28,7 +29,11 @@ You should have done (to clone only the trunk) :
 
     git tfs clone http://tfs:8080/tfs/DefaultCollection $/Repository/ProjectTrunk
 
+Note : It is highly recommanded to clone the root branch ( the branch that has no parents, here $/Repository/ProjectTrunk ) to be able to init the other branches after.
+If you clone the branch $/Repository/ProjectBranch, you will never able to init the root branch $/Repository/ProjectTrunk after.
+
 Then use `init-branch` like this :
+
 ### Init a TFS branches using auto-naming of your git branch
     git tfs init-branch $/Repository/ProjectBranch