git-gui: Improve pull error dialogs.
git-gui: Improve pull error dialogs.

Just like prior to a commit its only an informational message that
we refuse to perform a pull on a dirty working directory.  Therefore
we should not use an error icon.

Signed-off-by: Shawn O. Pearce <f01032651c12a22b2103346ba96b3b6b231f9d3c@spearce.org>
destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git