[evolution-data-server] EBookSqlite: Address runtime warnings from remove_leading_zeros() in unit tests

[Milan Crha <mcrha src gnome org>]

commit 592127c0e7631419e869f5bc28134f0e37b2bdfb
Author: Milan Crha <mcrha redhat com>
Date:   Tue Jan 21 18:55:50 2020 +0100

    EBookSqlite: Address runtime warnings from remove_leading_zeros() in unit tests

 src/addressbook/libedata-book/e-book-sqlite.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
---
diff --git a/src/addressbook/libedata-book/e-book-sqlite.c b/src/addressbook/libedata-book/e-book-sqlite.c
index 79ca346d6..82817ded5 100644
--- a/src/addressbook/libedata-book/e-book-sqlite.c
+++ b/src/addressbook/libedata-book/e-book-sqlite.c
@@ -3175,10 +3175,15 @@ remove_leading_zeros (gchar *number)
        gchar *trimmed = NULL;
        gchar *tmp = number;
 
-       g_return_val_if_fail (NULL != number, NULL);
+       if (!number)
+               return NULL;
 
        while ('0' == *tmp)
                tmp++;
+
+       if (tmp == number)
+               return number;
+
        trimmed = g_strdup (tmp);
        g_free (number);