[SCM-952] check-local-modification does not recognize new files (git)

**[D T](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=st-ddt)** opened **[SCM-952](https://issues.apache.org/jira/browse/SCM-952?redirect=false)** and commented

If I add a new file src/main/MyNewFile.txt to my project and run

mvn scm:check-local-modification

 
then the build completes successfully, showing only a warning regarding an unrecognized lines:

```java
[INFO] Scanning for projects...
[INFO]
[INFO] --------------< test:test >--------------
[INFO] Building Test 1.9.1-SNAPSHOT
[INFO] ----------------------------[ maven-plugin ]----------------------------
[INFO]
[INFO] --- maven-scm-plugin:1.11.2:check-local-modification (default-cli) @ test ---
[INFO] Executing: cmd.exe /X /C "git rev-parse --show-prefix"
[INFO] Working directory: C:\Users\test\git\test
[INFO] Executing: cmd.exe /X /C "git status --porcelain ."
[INFO] Working directory: C:\Users\test\git\test
[WARNING] Ignoring unrecognized line: ?? src/main/MyNewFile.txt
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.247 s
[INFO] Finished at: 2021-07-15T11:39:32+02:00
[INFO] ------------------------------------------------------------------------
```

**Expected result:**
Build failed, because there is a file that isn't ignored or commited.

```java
$ git --version
git version 2.32.0.windows.2
```

---

**Affects:** 1.11.2

Reproduce the issue with the check-local-modification goal and the shown git status --porcelain output containing an untracked file. Trace the Git handling that parses this output and determine how unrecognized lines are treated. Done means an unignored, uncommitted new file causes the Maven build to fail while ignored files remain unaffected.

Written by the indexing model from the issue text.