fix(git): use exact executable name

can conflict with git.cmd

relates to #315

src/segment_git.go

@@ -112,8 +112,6 @@ const (
 	BehindColor Property = "behind_color"
 	// AheadColor if set, the color to use when the branch is ahead and behind the remote
 	AheadColor Property = "ahead_color"
-
-	gitCommand = "git"
 )
 
 func (g *git) enabled() bool {
@@ -272,6 +270,10 @@ func (g *git) getStatusColor(defaultValue string) string {
 }
 
 func (g *git) getGitCommandOutput(args ...string) string {
+	gitCommand := "git"
+	if g.env.getRuntimeGOOS() == "windows" {
+		gitCommand = "git.exe"
+	}
 	args = append([]string{"--no-optional-locks", "-c", "core.quotepath=false", "-c", "color.status=false"}, args...)
 	val, _ := g.env.runCommand(gitCommand, args...)
 	return val

src/segment_git_test.go

@@ -59,6 +59,7 @@ func TestGetGitOutputForCommand(t *testing.T) {
 	want := "je suis le output"
 	env := new(MockedEnvironment)
 	env.On("runCommand", "git", append(args, commandArgs...)).Return(want, nil)
+	env.On("getRuntimeGOOS", nil).Return("unix")
 	g := &git{
 		env: env,
 	}
@@ -103,6 +104,7 @@ func setupHEADContextEnv(context *detachedContext) *git {
 	env.mockGitCommand(context.tagName, "describe", "--tags", "--exact-match")
 	env.mockGitCommand(context.origin, "name-rev", "--name-only", "--exclude=tags/*", context.origin)
 	env.mockGitCommand(context.onto, "name-rev", "--name-only", "--exclude=tags/*", context.onto)
+	env.On("getRuntimeGOOS", nil).Return("unix")
 	g := &git{
 		env: env,
 		repo: &gitRepo{
@@ -401,6 +403,7 @@ func TestParseGitStatsInvalidLine(t *testing.T) {
 func bootstrapUpstreamTest(upstream string) *git {
 	env := &MockedEnvironment{}
 	env.On("runCommand", "git", []string{"--no-optional-locks", "-c", "core.quotepath=false", "-c", "color.status=false", "remote", "get-url", "origin"}).Return(upstream, nil)
+	env.On("getRuntimeGOOS", nil).Return("unix")
 	props := &properties{
 		values: map[Property]interface{}{
 			GithubIcon:    "GH",