RFR: Limit path arguments to git to 64 at a time

[Erik Duveblad via github.com]

Hi all,

this commit limits the number of `Path` arguments we pass on to `git` to at most 64 at a time. This is too avoid too long command lines (since paths can be fairly long).

## Testing
- [x] `sh gradlew test` passes

Thanks,
Erik

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Commits:
 - 8ef4a0fb:	Limit path arguments to git to 64 at a time

Pull request:
https://git.openjdk.java.net/skara/pull/84

Webrev:
https://webrevs.openjdk.java.net/skara/84/webrev.00

Patch:
https://git.openjdk.java.net/skara/pull/84.diff

Fetch command:
git fetch https://git.openjdk.java.net/skara pull/84/head:pull/84