SCM APIs cause "ref HEAD is not a symbolic ref"

[Simone Tripodi]

Hi all mates,
I've been happily using the Maven SCM APIs to perform few operations "under
the hood" for my users, everything was working fine until stumbled in the
SCMException "Detecting the current branch failed: fatal: ref HEAD is not a
symbolic ref"
The scenario is: I am using the libraries below

       <dependency>
            <groupId>org.apache.maven.scm</groupId>
            <artifactId>maven-scm-api</artifactId>
            <version>${maven.scm.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.maven.scm</groupId>
            <artifactId>maven-scm-provider-gitexe</artifactId>
            <version>${maven.scm.version}</version>
        </dependency>
where <maven.scm.version>1.9.4</maven.scm.version>, the sequence of
operations that cause the error are:

            ScmVersion version = new ScmTag(version);
            ScmResult result = scmManager.checkOut(repository, new
ScmFileSet(appDir), version);
            ...
            result = scmManager.add(repository, new ScmFileSet(appDir,
newFile), commitMessage);
            ...
           result = scmManager.checkIn(repository, new ScmFileSet(
quickstartDir), version, commitMessage);
The error happens when invoking the checkIn, do you have any recommendation
on how to modify the operations sequence in order to make it working, when
checking out a tag?

Many thanks in advance, all the best!
-Simo

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