Error logged on repositories without "master" branch

[fjakop]

Some repositories just do not contain a "master" branch, e.g. https://github.com/RobinHerbots/jquery.inputmask.
When a repository of this kind is cached, every time a refresh happens, the log ist cluttered wit the following entries

Mai 17 13:16:22 bowerserver private-bower[16225]: [bower]  17/5/16 13:16:22   Error during "git reset --hard origin/master" in "/mnt/bowerserver/jquery.inputmask".
Mai 17 13:16:22 bowerserver private-bower[16225]: Output:
Mai 17 13:16:22 bowerserver private-bower[16225]: stdout:
Mai 17 13:16:22 bowerserver private-bower[16225]: stderr: fatal: ambiguous argument 'origin/master': unknown revision or path not in the working tree.
Mai 17 13:16:22 bowerserver private-bower[16225]: Use '--' to separate paths from revisions, like this:
Mai 17 13:16:22 bowerserver private-bower[16225]: 'git <command> [<revision>...] -- [<file>...]'
Mai 17 13:16:22 bowerserver private-bower[16225]: [bower]  17/5/16 13:16:22   Command failed: /bin/sh -c git reset --hard origin/master
Mai 17 13:16:22 bowerserver private-bower[16225]: fatal: ambiguous argument 'origin/master': unknown revision or path not in the working tree.
Mai 17 13:16:22 bowerserver private-bower[16225]: Use '--' to separate paths from revisions, like this:
Mai 17 13:16:22 bowerserver private-bower[16225]: 'git <command> [<revision>...] -- [<file>...]'
Mai 17 13:16:22 bowerserver private-bower[16225]:
Mai 17 13:16:22 bowerserver private-bower[16225]: undefined
Mai 17 13:16:22 bowerserver private-bower[16225]: Unhandled rejection Error: Command failed: /bin/sh -c git reset --hard origin/master
Mai 17 13:16:22 bowerserver private-bower[16225]: fatal: ambiguous argument 'origin/master': unknown revision or path not in the working tree.
Mai 17 13:16:22 bowerserver private-bower[16225]: Use '--' to separate paths from revisions, like this:
Mai 17 13:16:22 bowerserver private-bower[16225]: 'git <command> [<revision>...] -- [<file>...]'
Mai 17 13:16:22 bowerserver private-bower[16225]: at ChildProcess.exithandler (child_process.js:213:12)
Mai 17 13:16:22 bowerserver private-bower[16225]: at emitTwo (events.js:87:13)
Mai 17 13:16:22 bowerserver private-bower[16225]: at ChildProcess.emit (events.js:172:7)
Mai 17 13:16:22 bowerserver private-bower[16225]: at maybeClose (internal/child_process.js:821:16)
Mai 17 13:16:22 bowerserver private-bower[16225]: at Process.ChildProcess._handle.onexit (internal/child_process.js:211:5)

I would expect the log staying clean, even if there's no "master" branch which is not common but perfectly legal.

I'm using version 1.1.7.