filemerge: add a precheck for symlinks This will be used by internal merge tools.

filemerge: call precheck if available In upcoming patches we'll define a precheck function for some merge tools.

filemerge: add a before-merge callback to internal merge tools We're going to separate the pre-merge and merge steps for merge tools. The merge step will be specific to the tool, but the pre-merge step will be common to all merge tools that need it. However, some merge tools run checks *before* the pre-merge step. This callback will allow that to continue to work.

filemerge: indent filemerge.filemerge This will make upcoming patches much easier to review.

test-bundle-type: replace unbundle with debugbundle We now have a convenient command to look at bundle contents, let's use it.

bundle: extract the parsing of the bundle type in a function We are going to introduce significant extensions of the bundle parsing code to support creation of bundle2 through the bundle command. As an early step, we extract the logic in its own function.

changegroup: add version argument to getchangegroup For some obscure reasons (probably upsetting a Greek goddess), getchangegroup did not had a 'version' argument to control the changegroup version. We fixes this to allow cg02 to be used with 'hg bundle' in the future.

changegroup: add version argument to getlocalchangegroup For some obscure reasons (probably upsetting a Greek goddess), getlocalchangegroup did not have a 'version' argument to control the changegroup version. We fix this to allow cg02 to be used with 'hg bundle' in the future.

shelve: bundle using bundle2 if repository is general delta (issue4862) This will prevent expensive delta computation on bundling and is similar to what we do for strip backup.

shelve: move changegroup generation inside writebundle We will generate different changegroup if general delta is enabled so we gather this in the lower level function. There wasn't any good reason to have it in the main code anyway.