More explicit test of status panel content

Use Equals instead of Contains for asserting the status view content. This
solves the problem that we might assert Contains("↓2 repo"), but what it really
shows is "↑1↓2 repo", and the test still succeeds. At best this is confusing.

Also, this way we don't have to use the awkward DoesNotContain to check that it
really doesn't show a checkmark.

To do this, we need to fix two whitespace problems:
- there was always a space at the end for no reason. Simply remove it. It was
  added in efb51eee96, but from looking at that diff it seems it was added
  accidentally.
- there was a space at the beginning if the branch status was empty. This is
  actually a cosmetic problem, for branches without a status the text was
  indented by once space. Change this so that the space is added conditionally.
  It's a bit awkward that we have to use Decolorise here, but this will go away
  again later in this branch.

pkg/integration/tests/sync/push_with_credential_prompt.go

@@ -26,7 +26,7 @@ var PushWithCredentialPrompt = NewIntegrationTest(NewIntegrationTestArgs{
 		shell.CopyHelpFile("pre-push", ".git/hooks/pre-push")
 	},
 	Run: func(t *TestDriver, keys config.KeybindingConfig) {
-		t.Views().Status().Content(Contains("↑1 repo → master"))
+		t.Views().Status().Content(Equals("↑1 repo → master"))
 
 		t.Views().Files().
 			IsFocused().
@@ -50,7 +50,7 @@ var PushWithCredentialPrompt = NewIntegrationTest(NewIntegrationTestArgs{
 			Content(Contains("incorrect username/password")).
 			Confirm()
 
-		t.Views().Status().Content(Contains("↑1 repo → master"))
+		t.Views().Status().Content(Equals("↑1 repo → master"))
 
 		// try again with correct password
 		t.Views().Files().
@@ -67,7 +67,7 @@ var PushWithCredentialPrompt = NewIntegrationTest(NewIntegrationTestArgs{
 			Type("password").
 			Confirm()
 
-		t.Views().Status().Content(Contains("✓ repo → master"))
+		t.Views().Status().Content(Equals("✓ repo → master"))
 
 		assertSuccessfullyPushed(t)
 	},