Add more test and fix a typo in function docs

Signed-off-by: ziad hany <ziadhany2016@gmail.com>

Author: ziadhany

src/univers/gentoo.py

@@ -185,7 +185,7 @@ def vercmp(ver1, ver2):
 
 def bump(ver):
     """
-    Return a new version object where the next to the last revision number
+    Return a new version where the next to the last revision number
     is one greater (e.g., 5.3.1 => 5.4) i.e., incrementing this GentooVersion
     last numeric segment.
     """

tests/test_gentoo.py

@@ -37,4 +37,6 @@ def test_gentoo_bump():
     assert GentooVersion("2.23.3").bump() == "2.24"
     assert GentooVersion("2.24.3").bump() == "2.25"
     assert GentooVersion("2.25.4").bump() == "2.26"
-    assert GentooVersion("2.26.2").bump() == "2.27"
+    assert GentooVersion("1.3.8b").bump() == "1.4"
+    assert GentooVersion("9.9_p2").bump() == "10"
+    assert GentooVersion("0.13.4-r2").bump() == "0.14"