Reproduction steps

build libgit2 with examples (lg2), then

mkdir test
cd test
git init
git remote add origin https://github.com:/libgit2/libgit2.git
lg2 fetch origin

Expected behavior

The repository is fetched

Actual behavior

Bad news:
 malformed URL 'https://github.com:/libgit2/libgit2.git'

Version of libgit2 (release number or SHA1)

e50d138

Operating system(s) tested

Gentoo linux