[bitbake][wrynose][2.18][PATCH v2 5/8] fetch2/crate: guard against empty version list

From: Thomas Perrot <[email protected]>

Both latest_versionstring() and latest_versionstring_from_index() would
raise IndexError on versions[-1] if the fetched index returns no usable
versions.
Return ("", "") in that case, consistent with what callers expect when
no upstream version can be determined.

Signed-off-by: Thomas Perrot <[email protected]>
Signed-off-by: Mathieu Dubois-Briand <[email protected]>
Signed-off-by: Richard Purdie <[email protected]>
(cherry picked from commit ffdc2a02693379d7ead0f7b940111340843d49a4)
Signed-off-by: Yoann Congal <[email protected]>
---
 lib/bb/fetch2/crate.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/bb/fetch2/crate.py b/lib/bb/fetch2/crate.py
index d84bae0bc..eb1fd5719 100644
--- a/lib/bb/fetch2/crate.py
+++ b/lib/bb/fetch2/crate.py
@@ -164,7 +164,7 @@ class Crate(Wget):
         versions = [(0, i["num"], "") for i in json_data["versions"]]
         versions = sorted(versions, key=cmp_to_key(bb.utils.vercmp))
 
-        return (versions[-1][1], "")
+        return (versions[-1][1], "") if versions else ("", "")
 
     def latest_versionstring_from_index(self, ud, d):
         """
@@ -182,4 +182,4 @@ class Crate(Wget):
                 versions.append((0, data["vers"], ""))
 
         versions = sorted(versions, key=cmp_to_key(bb.utils.vercmp))
-        return (versions[-1][1], "")
+        return (versions[-1][1], "") if versions else ("", "")