Fix issue where build steps are duplicated in the output

This fixes an issue where the build output for the "Steps" would look like:
```
Step 1: RUN echo hi echo hi
```
instead of
```
Step 1: RUN echo hi
```

Also, I noticed that there were no checks to make sure invalid Dockerfile
cmd flags were caught on cmds that didn't use cmd flags at all. They would
have been caught on the cmds that had flags, but cmds that didn't bother
to add a new code for flags would have just ignored them.  So, I added
checks to each cmd to flag it.

Added testcases for issues.

Signed-off-by: Doug Davis <dug@us.ibm.com>
Upstream-commit: 08b7f30fcd050244026098673b19700485308b5a
Component: engine

components/engine/integration-cli/docker_cli_build_test.go

@@ -5349,3 +5349,38 @@ RUN cat /proc/self/cgroup
 		c.Fatalf("unexpected failure when running container with --cgroup-parent option - %s\n%v", string(out), err)
 	}
 }
+
+func (s *DockerSuite) TestBuildNoDupOutput(c *check.C) {
+	// Check to make sure our build output prints the Dockerfile cmd
+	// property - there was a bug that caused it to be duplicated on the
+	// Step X  line
+	name := "testbuildnodupoutput"
+
+	_, out, err := buildImageWithOut(name, `
+  FROM busybox
+  RUN env`, false)
+	if err != nil {
+		c.Fatalf("Build should have worked: %q", err)
+	}
+
+	exp := "\nStep 1 : RUN env\n"
+	if !strings.Contains(out, exp) {
+		c.Fatalf("Bad output\nGot:%s\n\nExpected to contain:%s\n", out, exp)
+	}
+}
+
+func (s *DockerSuite) TestBuildBadCmdFlag(c *check.C) {
+	name := "testbuildbadcmdflag"
+
+	_, out, err := buildImageWithOut(name, `
+  FROM busybox
+  MAINTAINER --boo joe@example.com`, false)
+	if err == nil {
+		c.Fatal("Build should have failed")
+	}
+
+	exp := `"Unknown flag: boo"`
+	if !strings.Contains(out, exp) {
+		c.Fatalf("Bad output\nGot:%s\n\nExpected to contain:%s\n", out, exp)
+	}
+}