rebase from ambiguous ref discards changes

[Keith Packard <keithp@keithp.com>]

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So, I started with a very simple repository

---*--- master
    \
     -- origin/master

From master, I did

$ git-rebase origin/master
warning: refname 'master' is ambiguous.
First, rewinding head to replay your work on top of it...
HEAD is now at 2a8592f... Fix G33 GTT stolen mem range
Fast-forwarded master to origin/master.
$

Note the lack of the usual 'Applying <patch>' messages.

checking the tree, I now had

---*
    \
     -- origin/master
        master

with my patch lost.

recovering my patch (having the ID in my terminal window from the
commit), I named it 'master-with-fix'

---*--- master-with-fix
    \
     -- origin/master
        master

Now the rebase from 'master-with-fix worked as expected:

$ git-rebase origin/master
First, rewinding head to replay your work on top of it...
HEAD is now at 2a8592f... Fix G33 GTT stolen mem range

Applying Switch to pci_device_map_range/pci_device_unmap_range APIs.

Adds trailing whitespace.
.dotest/patch:225:      
Adds trailing whitespace.
.dotest/patch:226:      if (IS_I965G(pI830)) 
Adds trailing whitespace.
.dotest/patch:446:
dev->regions[mmio_bar].size, 
Adds trailing whitespace.
.dotest/patch:449:    
warning: 4 lines add whitespace errors.
Wrote tree cd373666254d56a137d282deeb15a2ccaf8da22b
Committed: 286f5df0b62f571cbb4dbf120679d3af029b8775
$ 

And the tree looks right too:

--- origin/master --- master-with-fix
    master
       
Seems like there's something going on when 'master' is ambiguous, or
perhaps some other problem.

This is all from version 1.5.3, but I think I've seen this on 1.5.2 as
well.

Git made me sad today; I'm not sure it's ever disappointed like this
before.

-- 
keith.packard@intel.com

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