tests/test-largefiles-small-disk.t

repoview: do not crash when localtags refers to non existing revisions

This fixes a crash that may happen when using mercurial 3.0.x.

The _gethiddenblockers function assumed that the output of tags.readlocaltags()
was a dict mapping tags to of valid nodes. However this was not necessarily the
case. When a repository had obsolete revisions and had local tag pointing to a
non existing revision was found, many mercurial commands would crash.

This revision fixes the problem by removing any tags from the output of
tags.readlocaltags() which point to invalid nodes.

We may want to add a warning when this happens (although it might be
annoying to get that warning for every command, possibly even more than once per
command).

A test for this problem has been added to test-obsolete.t. Without this fix the
test would output:

  $ hg tags
  abort: 00changelog.i@3816541e5485: no node!
  [255]

Instead of:

  $ hg tags
  tiptag                             2:3816541e5485
  tip                                2:3816541e5485
  visible                            0:193e9254ce7e

Test how largefiles abort in case the disk runs full

  $ cat > criple.py <<EOF
  > import os, errno, shutil
  > from mercurial import util
  > #
  > # this makes the original largefiles code abort:
  > def copyfileobj(fsrc, fdst, length=16*1024):
  >     fdst.write(fsrc.read(4))
  >     raise IOError(errno.ENOSPC, os.strerror(errno.ENOSPC))
  > shutil.copyfileobj = copyfileobj
  > #
  > # this makes the rewritten code abort:
  > def filechunkiter(f, size=65536, limit=None):
  >     yield f.read(4)
  >     raise IOError(errno.ENOSPC, os.strerror(errno.ENOSPC))
  > util.filechunkiter = filechunkiter
  > #
  > def oslink(src, dest):
  >     raise OSError("no hardlinks, try copying instead")
  > util.oslink = oslink
  > EOF

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "largefiles =" >> $HGRCPATH

  $ hg init alice
  $ cd alice
  $ echo "this is a very big file" > big
  $ hg add --large big
  $ hg commit --config extensions.criple=$TESTTMP/criple.py -m big
  abort: No space left on device
  [255]

The largefile is not created in .hg/largefiles:

  $ ls .hg/largefiles
  dirstate

The user cache is not even created:

  >>> import os; os.path.exists("$HOME/.cache/largefiles/")
  False

Make the commit with space on the device:

  $ hg commit -m big

Now make a clone with a full disk, and make sure lfutil.link function
makes copies instead of hardlinks:

  $ cd ..
  $ hg --config extensions.criple=$TESTTMP/criple.py clone --pull alice bob
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  updating to branch default
  getting changed largefiles
  abort: No space left on device
  [255]

The largefile is not created in .hg/largefiles:

  $ ls bob/.hg/largefiles
  dirstate