Fix for https://github.com/ktoso/maven-git-commit-id-plugin/issues/149

[TheSnoozer]

As discussed in #149
Using "...-dirty" as default dirty-marker.

[ktoso]

Almost :-)
Would you mind to make the tests pass on travis?

Current failure is

java.lang.RuntimeException: Failed to execute git command (`git describe --dirty=-dirty --match=v2.1.8 --abbrev=7` @ /home/travis/build/ktoso/maven-git-commit-id-plugin/target/sandbox/my-pom-project/my-jar-module)!
    at pl.project13.maven.git.NativeGitProvider.runGitCommand(NativeGitProvider.java:277)
    at pl.project13.maven.git.NativeGitProvider.tryToRunGitCommand(NativeGitProvider.java:242)
    at pl.project13.maven.git.NativeGitProvider.getGitDescribe(NativeGitProvider.java:92)
    at pl.project13.maven.git.GitDataProvider.maybePutGitDescribe(GitDataProvider.java:120)
    at pl.project13.maven.git.GitDataProvider.loadGitData(GitDataProvider.java:88)
    at pl.project13.maven.git.GitCommitIdMojo.loadGitDataWithNativeGit(GitCommitIdMojo.java:508)
    at pl.project13.maven.git.GitCommitIdMojo.loadGitData(GitCommitIdMojo.java:491)
    at pl.project13.maven.git.GitCommitIdMojo.execute(GitCommitIdMojo.java:351)
    at pl.project13.maven.git.GitCommitIdMojoIntegrationTest.runGitDescribeWithMatchOption(GitCommitIdMojoIntegrationTest.java:649)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)

[TheSnoozer]

Sure.
Somehow the travis for the maven-git-commit-id-plugin itself is fail with the same exception....

https://travis-ci.org/ktoso/maven-git-commit-id-plugin/builds

I will review this ASAP (propably tomorrow).
Mighty be again some troubles with travis' git shallow copy...

failing since:
44bc422

[ktoso]

Ouch, thanks for noticing. I'll be able to look into it on sunday :)

[TheSnoozer]

@ktoso,
travis works for know.
Not sure what this original exception came from, locally had no problem with it.
It might be that travis makes only a shallow copy of the repository or something...
When it comes back at some time, there should somehow a better fix instead of just using some other commits.

[ktoso]

Merged this in manually.