[GITEA] Add password length check on install page

- Resolves #271
- Ensure that the adminstrator password is at least `MIN_PASSWORD_LENGTH`.

(cherry picked from commit 28cb04c3f5)
(cherry picked from commit 95371ebd92)
(cherry picked from commit a134288ab6)
(cherry picked from commit 4202f052cb)
(cherry picked from commit 510b7467d3)
(cherry picked from commit f3a6e1f121)
(cherry picked from commit f340508819)

routers/install/install.go

@@ -366,6 +366,12 @@ func SubmitInstall(ctx *context.Context) {
 			ctx.RenderWithErr(ctx.Tr("form.password_not_match"), tplInstall, form)
 			return
 		}
+		if len(form.AdminPasswd) < setting.MinPasswordLength {
+			ctx.Data["Err_Admin"] = true
+			ctx.Data["Err_AdminPasswd"] = true
+			ctx.RenderWithErr(ctx.Tr("auth.password_too_short", setting.MinPasswordLength), tplInstall, form)
+			return
+		}
 	}
 
 	// Init the engine with migration