Fix the expanded layout of the branches panel (half and full screen modes) (#5413)

If the showDivergenceFromBaseBranch config is not none, the expanded
branches panel would no longer show the remote branch and subject; the
reason was that we padded the name all the way to the right edge of the
view so that the divergence information is right-aligned.

To fix this, we simply don't right-align the divergence in half or full
screen mode. This is a bit unfortunate, but it's hard to do any better,
because we don't know the width of our column in advance. One thing I
tried is to make the divergence a separate column in that case (with an
explicit right-alignment set on it via getColumnAlignments; however,
this makes it harder to properly truncate the name when the window is
too narrow.

pkg/gui/presentation/branches.go

@@ -145,7 +145,13 @@ func getBranchDisplayStrings(
 	}
 
 	if divergence != "" {
-		paddingNeededForDivergence -= utils.StringWidth(utils.Decolorise(coloredName)) - 1
+		if fullDescription {
+			// don't right-align the divergence in half or full screen mode, since other fields
+			// follow in that case and we don't know the width of our column
+			paddingNeededForDivergence = 1
+		} else {
+			paddingNeededForDivergence -= utils.StringWidth(utils.Decolorise(coloredName)) - 1
+		}
 		if paddingNeededForDivergence > 0 {
 			coloredName += strings.Repeat(" ", paddingNeededForDivergence)
 			coloredName += style.FgCyan.Sprint(divergence)