Describe the bug
UnifiedDiffReader.parseUnifiedDiff throws UnifiedDiffParserException on a patch which apparently looks good:

https://git.stg.centos.org/rpms/adcli/blob/f29/f/0015-make-Samba-data-tool-configurable.patch

To Reproduce
Run this program: https://gist.github.com/moio/e6357cdd23d7645466c005004c4aa95c

(contains the literal patch as a string)

Expected behavior

No Exceptions.

Actual behavior

Dec 11, 2020 5:40:52 PM com.github.difflib.unifieddiff.UnifiedDiffReader processLine
WARNING: >>> no rule matched diff --git a/library/adenroll.c b/library/adenroll.c
Exception in thread "main" com.github.difflib.unifieddiff.UnifiedDiffParserException: expected data line not found
at com.github.difflib.unifieddiff.UnifiedDiffReader.parse(UnifiedDiffReader.java:104)
at com.github.difflib.unifieddiff.UnifiedDiffReader.parseUnifiedDiff(UnifiedDiffReader.java:146)
at Main.main(Main.java:303)
...

System

• Java version: openjdk-11
• Version: 4.9

Suspect

This diff line has a --git parameter which is not understood by the parser:

diff --git a/configure.ac b/configure.ac

Notes

👋 java-diff-utils maintainers! Thanks for this library, it's helping me considerably! I am happy to test any PR to fix this.