tests/test-symlink-os-yes-fs-no.py

rebase: improve error message for --base being empty or causing emptiness

Before it just said 'nothing to rebase'.

Now 'if "base" is an empty set:
  abort: empty "base" revision set - can't compute rebase set

If the set of changesets to rebase can't be found from "base", it will fail as
before but with more explanation of what the problem was.

The name of the "base" option is not obvious - it is more like "samples
identifying the branch to rebase". The error messages for problems with the
specified "base" value will use that term and might thus also not be obvious,
but at least they are consistent with the option name. The name "base" will not
be used if the base only was specified implicitly as the working directory
parent.

import os, sys, time
from mercurial import hg, ui, commands, util

TESTDIR = os.environ["TESTDIR"]
BUNDLEPATH = os.path.join(TESTDIR, 'bundles', 'test-no-symlinks.hg')

# only makes sense to test on os which supports symlinks
if not getattr(os, "symlink", False):
    sys.exit(80) # SKIPPED_STATUS defined in run-tests.py

u = ui.ui()
# hide outer repo
hg.peer(u, {}, '.', create=True)

# clone with symlink support
hg.clone(u, {}, BUNDLEPATH, 'test0')

repo = hg.repository(u, 'test0')

# wait a bit, or the status call wont update the dirstate
time.sleep(1)
commands.status(u, repo)

# now disable symlink support -- this is what os.symlink would do on a
# non-symlink file system
def symlink_failure(src, dst):
    raise OSError(1, "Operation not permitted")
os.symlink = symlink_failure

# dereference links as if a Samba server has exported this to a
# Windows client
for f in 'test0/a.lnk', 'test0/d/b.lnk':
    os.unlink(f)
    fp = open(f, 'wb')
    fp.write(util.readfile(f[:-4]))
    fp.close()

# reload repository
u = ui.ui()
repo = hg.repository(u, 'test0')
commands.status(u, repo)

# try cloning a repo which contains symlinks
u = ui.ui()
hg.clone(u, {}, BUNDLEPATH, 'test1')