More informative crash on invalid working directory

[asbjornu]

I managed to invoke GitVersion.exe with the argument showconfig instead of /showconfig and got the following exception:

Unhandled Exception: System.ComponentModel.Win32Exception: The directory name is invalid
   at System.Diagnostics.Process.StartWithCreateProcess(ProcessStartInfo startInfo)
   at System.Diagnostics.Process.Start(ProcessStartInfo startInfo)
   at GitVersion.Helpers.ProcessHelper.Start(ProcessStartInfo startInfo)
   at GitVersion.Helpers.ProcessHelper.Run(Action`1 output, Action`1 errorOutput, TextReader input, String exe, String args, String workingDirectory, KeyValuePair`2[] environmentalVariables)
   at GitVersion.LibGitExtensions.DumpGraph(String workingDirectory, Action`1 writer, Nullable`1 max Commits)
   at GitVersion.Program.VerifyArgumentsAndRun()
   at GitVersion.Program.Main()

This PR improves this exception somewhat by at least letting the user know what the name of the directory it can't find is:

INFO [11/11/15 12:38:31:12] Working directory: showconfig
ERROR [11/11/15 12:38:31:15] An unexpected error occurred:
System.IO.DirectoryNotFoundException: Can't find the .git directory in showconfig
   at GitVersion.GitPreparer.GetProjectRootDirectory()
   at GitVersion.ExecuteCore.ExecuteGitVersion(IFileSystem fileSystem, String targetUrl, String dyna
micRepositoryLocation, Authentication authentication, String targetBranch, Boolean noFetch, String w
orkingDirectory, String commitId)
   at GitVersion.SpecifiedArgumentRunner.Run(Arguments arguments, IFileSystem fileSystem)
   at GitVersion.Program.VerifyArgumentsAndRun()
INFO [11/11/15 12:38:31:15]
INFO [11/11/15 12:38:31:15] Here is the current git graph (please include in issue):
INFO [11/11/15 12:38:31:15] Showing max of 100 commits
INFO [11/11/15 12:38:31:16] ERROR: The directory showconfig doesn't exist.

I'm not sure how the process is able to advance to the exception now being thrown in GitPreparer.GetProjectRootDirectory(), but I find this a worthwile improvement nonetheless. I will attempt at writing a test for this, but please have a look at the PR and let me know if I should do anything about it.

[JakeGinnivan]

Is this r# splitting it up? We should add the setting to stop this automatically happening (for consistency reasons) into the solution DotSettings file

[asbjornu]

Yes. I'm actually not entirely sure if it is my machine-level R# doing this or the local ("team shared") sln.DotSettings file. Either way, I agree that the local one should specify this explicitly.

[pkiers]

Hi,

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[email protected]