[bug 0.11] commit succeeds with conflict markers in the file

[Jari Aalto]

Consider this

    $ bzr merge ../a
    <conflict, hack, hack, remove unneeded files>
    $ bzr resolved file.txt
    $ bzr ci -m "Done"

Ah, but there still was left confluct markers that escaped the eyes of
the developer, who *thought* all was resolved, when it was not:

    <<<<<<< TREE
    ...
    =======
    ...
    >>>>>>> MERGE-SOURCE

Nonetheless, up we go and "bzr ci" added the file to wait for better
time to mess up the build.

SUGGESTION

Please add checking for conflict markers and refuse to commit

    bzr ci ...
    ERROR: conflict markers found in file.txt (to commit anyway, use -f)
    
unless option -f|--force is used (ahem, ci does not seem to have that
optoion yet):

    bzr ci --force ...

No interactive questions this time, pretty please.

Jari