.clang-format

test: fix self._testdir to use the right mercurial library during testing

Currently if you run tests from some other directory other than the
`../tests/`, you will get a warning stating

```
warning: Testing with unexpected mercurial lib: mercurial
         (expected /tmp/hgtests.xxxxxx/install/lib/python/mercurial)
```

This is because the current directory being added to the 'PATH', if the
`self._testdir != runtestdir`, owing to this line

```
if self._testdir != runtestdir:
    path = [self._testdir] + path
```

Also say you ran the tests from the hg base directory,
because directory is being added in the PATH (see the above snippet, at
that stage the `self._testdir` has the value as `cwd`, owing to a faulty
initialization). And since the current directory already has the 'hg',
that is used in place of the hg that is installed for the testing purposes
in `/tmp/hgtests.xxxxxx/...`.

Differential Revision: https://phab.mercurial-scm.org/D5199

BasedOnStyle: LLVM
IndentWidth: 8
UseTab: ForIndentation
BreakBeforeBraces: Linux
AllowShortIfStatementsOnASingleLine: false
IndentCaseLabels: false
AllowShortBlocksOnASingleLine: false
AllowShortFunctionsOnASingleLine: false
IncludeCategories:
  - Regex:           '^<'
    Priority:        1
  - Regex:           '^"'
    Priority:        2