merge transplanted cset back from crew-stable

Fix python2.3 incompatibility introduced by a2b13cac0922.

run-tests.py: Make tests run with python2.3 if HGTEST_* is set. optparse of python2.3 does not transform default values to the specified type so e.g. "HGTEST_JOBS=4" (introduced in 07c3cd695b48) causes tests to abort, because options.jobs is set to '4' instead of the number 4.

Ignore dummy copies in dirstate and localrepo.filecommit()

context: fix workingctx.fileflags() execute bit

sshserver: Don't try to close fp if mkstemp failed

Add a normalize() method to dirstate This method returns the normalised form of a path. This is - the form in the dirstate, if available, or - the form on disk, if available, or - the form passed on the command line normalize() is called on the type-'f' result of statwalk. This fixes issues 910 and 1092

Add a new function, fspath The function, given a relative filename and a root, returns the filename modified to use the case actually stored in the filesystem (or None if the file does not exist). The returned name is relative to the root, but retains the path separators used in the input path. (This is not strictly necessary, but retaining the path separators minimises misleading test suite failures). A win32-specific implementation (using win32api.FindFiles) is possible, but it has not been implemented as testing seems to demonstrate that the win32-specific code is not significantly faster (thanks to the caching of results in the generic code).

Add a folding() method to dirstate The method returns True if the dirstate is on a case folding filesystem.

update: add "(nobackup)" to help text of option --clean