cmd/util: fix error handling for parseArgsWithGitBranchMR

The parse logic to get the MR ID from remote and/or branch name was kinda
confusing:

1) the variable names were non-obvious
2) the error code was being ignored because it was being used as part of the
logic itself: it was fine to fail.

However, after the commit 69ae19e ("cmd: fix return value checks and
statements") was introduced, the error handling broke the logic.

To make things clearer and also to fix the breakage, this patch changed the
variable names and considered the error returning value to make sure we can
safely return with a valid ID value (in case the actual MR ID was used and
not the remote and/or branch name).

It's a soft revert of the commit 69ae19e ("cmd: fix return value checks
and statements") in this specific codepath, but still avoids golint
complaining about an error returning value being ignored.

Signed-off-by: Bruno Meneguele <bmeneg@redhat.com>

cmd/util.go

@@ -175,12 +175,10 @@ func parseArgsRemoteAndBranch(args []string) (string, string, error) {
 	}
 
 	remote, branch, err := parseArgsRemoteAndString(args)
-	if branch == "" && err == nil {
-		branch, err = git.CurrentBranch()
-	}
-
 	if err != nil {
 		return "", "", err
+	} else if branch == "" {
+		branch, err = git.CurrentBranch()
 	}
 
 	remoteBranch, _ := git.UpstreamBranch(branch)
@@ -311,38 +309,33 @@ func parseArgsRemoteAndString(args []string) (string, string, error) {
 // If no number is specified, the MR id associated with the given branch
 // is returned, using the current branch as fallback.
 func parseArgsWithGitBranchMR(args []string) (string, int64, error) {
-	var (
-		s      string
-		branch string
-		err    error
-	)
-	s, i, err := parseArgsRemoteAndID(args)
+	rn, id, err := parseArgsRemoteAndID(args)
+	if err == nil && id != 0 {
+		return rn, id, nil
+	}
+
+	rn, branch, err := parseArgsRemoteAndString(args)
 	if err != nil {
 		return "", 0, err
 	}
 
-	if i == 0 {
-		s, branch, err = parseArgsRemoteAndString(args)
-		if err != nil {
-			return "", 0, err
-		}
+	rn, err = getRemoteName(rn)
+	if err != nil {
+		return "", 0, err
+	}
 
-		s, err = getRemoteName(s)
-		if err != nil {
-			return "", 0, err
-		}
+	if branch == "" {
+		id = int64(getCurrentBranchMR(rn))
+	} else {
+		id = int64(getBranchMR(rn, branch))
+	}
 
-		if branch == "" {
-			i = int64(getCurrentBranchMR(s))
-		} else {
-			i = int64(getBranchMR(s, branch))
-		}
-		if i == 0 {
-			fmt.Println("Error: Cannot determine MR id.")
-			os.Exit(1)
-		}
+	if id == 0 {
+		err = fmt.Errorf("cannot determine MR id")
+		return "", 0, err
 	}
-	return s, i, nil
+
+	return rn, id, nil
 }
 
 // filterCommentArg separate the case where a command can have both the