Merging in ChangeSetDiffTool is broken

[Jan Vrany]

Sometimes, after merging changes and saving result, output file still
contains <conflict> lines.

Steps to reproduce:

1. Download attached files (Object.*), save them into a directory, say /tmp/mergebug
2. In workspace, evaluate:

| spec |

spec :=  Tools::ChangeSetDiffInfo 
        specA: (Tools::ChangeSetSpec file: '/tmp/mergebug/Object.st.local')
        specB: (Tools::ChangeSetSpec file: '/tmp/mergebug/Object.st.other')
        specBase: (Tools::ChangeSetSpec file: '/tmp/mergebug/Object.st.base')
        specMerge: (Tools::ChangeSetSpec file: '/tmp/mergebug/Object.st').  

Tools::ChangeSetDiffTool new
    open;
    fileMenuOpenOnDiffInfo: spec
                                    

3. Merge all differences by using version B (using yellow B button in the middle bar on right.
4. Click Save

Now check that resulting Object.st does not contain any lines
like <conflict>