cargo2ebuild: Fix upper bounds to exclude pre-releases.

The _alpha suffix is needed because pre-release versions are treated as less
than the actual release by portage so 3.0.0_beta2 is treated as less than
3.0.0. Consequently, 3.0.0_beta2 may satisfy the requirement >=2.0.1:= <3.0.0
for portage but not meet the requirement for cargo. Adding the _alpha suffix
covers this edge case.

BUG=b:197410541
TEST=run cargo2ebuild for dbus-codegen.

Change-Id: I6fd25715f1088ac5bc267d86918171141e45e00f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/3113531
Tested-by: Allen Webb <allenwebb@google.com>
Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Commit-Queue: Allen Webb <allenwebb@google.com>
1 file changed