tests: remove 'hghave symlink' from test-import-git.t The test had a long chain of commits depending on execbits in some of first commits. The hashes are checked throughout the file, so there was no elegant way to make it pass both with and without execbits. We now rollback the execbits-or-not commits and make a stable change instead. The hash chain is thus updated once but is now a bit more stable. The test coverage should be unaltered.

tests: remove 'hghave symlink' from test-convert-svn-sink.t The symlink was present all over the test and could not easily be guarded with #if. Symlink testing is now moved to a separate #if section. All the relevant test coverage should unaltered.

tests: convert some 'hghave symlink' to #if This will enable some tests for windows.

tests: drop a couple of unnecessary 'hghave symlink'

tests: use the right directory for running hghave from run-tests.py

tests: make .t tests stop immediately if a cd fails This prevents tests from escaping from TESTTMP as a consequence of a failing directory creation.