[MERGE] Minor help fixes for add, commit, export

[Ian Clatworthy]

Aaron Bentley wrote:
> Aaron Bentley has voted -0.
> Status is now: Approved
> Comment:
> Adding info about selected-file commits and merge is fine.  Removing 
> information about selected-file commits without merge doesn't make sense.
>
> For details, see: 
> http://bundlebuggy.aaronbentley.com/request/%3C46105D29.2070607%40internode.on.net%3E 
>
>
Aaron,

Can you briefly explain when exactly a selected file commit will fail? 
And why that's a reasonable limitation for commit to have?

Here's the text I took out:

"A selected-file commit may fail in some cases where the committed
tree would be invalid, such as trying to commit a file in a
newly-added directory that is not itself committed."


 From the experiments that Martin and I did at last week's sprint, the 
text after "such as" was wrong. I'm happy to put back in the text up 
until the comma but I'd dearly love to provide a clear example re what 
constitutes an invalid tree. FWIW, when going through the man page, the 
reason I questioned this paragraph originally was because the add 
command makes the point of how it does the right (intelligent) thing:

"Adding a file whose parent directory is not versioned will implicitly 
add the parent, and so on up to the root. This means you should never 
need to explicitly add a directory, they'll just get added when you add 
a file in the directory."

The replaced paragraph stood out because it implied that commit lacked 
the intelligence of add. Now the issue with commit and invalid trees 
could well be completely different. If that's the case, I think we need 
to somehow document it better so that new users get the right mental 
model from the start.

Ian C.