Handle pending actions properly in git commands that require credentials

I don't know if this is a hack or not: we run a git command and increment the pending action
count to 1 but at some point the command requests a username or password, so we need to prompt
the user to enter that. At that point we don't want to say that there is a pending action,
so we decrement the action count before prompting the user and then re-increment it again afterward.

Given that we panic when the counter goes below zero, it's important that it's not zero
when we run the git command (should be impossible anyway).

I toyed with a different approach using channels and a long-running goroutine that
handles all commands that request credentials but it feels over-engineered compared to this
commit's approach.

pkg/commands/oscommands/cmd_obj_runner_test.go

@@ -15,6 +15,18 @@ func getRunner() *cmdObjRunner {
 	}
 }
 
+func toChanFn(f func(ct CredentialType) string) func(CredentialType) <-chan string {
+	return func(ct CredentialType) <-chan string {
+		ch := make(chan string)
+
+		go func() {
+			ch <- f(ct)
+		}()
+
+		return ch
+	}
+}
+
 func TestProcessOutput(t *testing.T) {
 	defaultPromptUserForCredential := func(ct CredentialType) string {
 		switch ct {
@@ -99,7 +111,7 @@ func TestProcessOutput(t *testing.T) {
 			reader := strings.NewReader(scenario.output)
 			writer := &strings.Builder{}
 
-			runner.processOutput(reader, writer, scenario.promptUserForCredential)
+			runner.processOutput(reader, writer, toChanFn(scenario.promptUserForCredential))
 
 			if writer.String() != scenario.expectedToWrite {
 				t.Errorf("expected to write '%s' but got '%s'", scenario.expectedToWrite, writer.String())