git grep prints colon instead of slash

[Marc Gonzalez <marc.w.gonzalez@free.fr>]

Hello,

I'm using an older version of git, so this particular issue might have
already been fixed.

$ git --version
git version 2.17.1


If I specify the branch to explore, git grep prints a colon instead of
a slash in the path:

$ git grep arm,coresight-tmc master:Documentation/devicetree
master:Documentation/devicetree:bindings/arm/coresight.txt:                     "arm,coresight-tmc", "arm,primecell";
master:Documentation/devicetree:bindings/arm/coresight.txt:             compatible = "arm,coresight-tmc", "arm,primecell";
                               ^
                              HERE

There is no such issue when the branch is not specified:

$ git grep arm,coresight-tmc Documentation/devicetree
Documentation/devicetree/bindings/arm/coresight.txt:                    "arm,coresight-tmc", "arm,primecell";
Documentation/devicetree/bindings/arm/coresight.txt:            compatible = "arm,coresight-tmc", "arm,primecell";
                        ^
                    NO ISSUE


Is this expected behavior?
The spurious colon prevents one from simply copy/pasting the output.

Regards.